[30] It is difficult to see why copper scales (_squamae aeris_--copper

oxide?) are added, unless it be to collect a small ratio of copper in

the ore. This additional copper is not mentioned again, however. The

whole of this statement is very confused.

[31] This old story runs that Hiero, King of Syracuse, asked Archimedes

to tell him whether a crown made for him was pure gold or whether it

contained some proportion of silver. Archimedes is said to have puzzled

over it until he noticed the increase in water-level upon entering his

bath. Whereupon he determined the matter by immersing bars of pure gold

and pure silver, and thus determining the relative specific weights. The

best ancient account of this affair is to be found in Vitruvius, IX,

Preface. The story does not seem very probable, seeing that

Theophrastus, who died the year Archimedes was born, described the

touchstone in detail, and that it was of common knowledge among the

Greeks before (see note 37). In any event, there is not sufficient

evidence in this story on which to build the conclusion of Meyer (Hist.

of Chemistry, p. 14) and others, that, inasmuch as Archimedes was unable

to solve the problem until his discovery of specific weights, therefore

the Ancients could not part gold and silver. The probability that he did

not want to injure the King's jewellery would show sufficient reason for

his not parting these metals. It seems probable that the Ancients did

part gold and silver by cementation. (See note on p. 458).

[32] The Alchemists (with whose works Agricola was familiar--_vide_

preface) were the inventors of nitric acid separation. (See note on p.

460).

[33] Parting gold and silver by nitric acid is more exhaustively

discussed in Book X. and note 10, p. 443.

[34] The lesser weights, probably.

[35] Lead and Tin seem badly mixed in this paragraph.

[36] It is not clear what is added.

[37] HISTORICAL NOTE ON TOUCHSTONE. (_Coticula_.

_Interpretatio_,--_Goldstein_). Theophrastus is, we believe, the first

to describe the touchstone, although it was generally known to the

Greeks, as is evidenced by the metaphors of many of the poets,--Pindar,

Theognis, Euripides, etc. The general knowledge of the constituents of

alloys which is implied, raises the question as to whether the Greeks

did not know a great deal more about parting metals, than has been

attributed to them. Theophrastus says (78-80): "The nature of the stone

which tries gold is also very wonderful, as it seems to have the same

power with fire; which is also a test of that metal. Some people have

for this reason questioned the truth of this power in the stone, but

their doubts are ill-founded, for this trial is not of the same nature

or made in the same manner as the other. The trial by fire is by the

colour and by the quantity lost by it; but that by the stone is made

only by rubbing the metal on it; the stone seeming to have the power to

receive separately the distinct particles of different metals. It is

said also that there is a much better kind of this stone now found out,

than that which was formerly used; insomuch that it now serves not only

for the trial of refined gold, but also of copper or silver coloured

with gold; and shows how much of the adulterating matter by weight is

mixed with gold; this has signs which it yields from the smallest weight

of the adulterating matter, which is a grain, from thence a colybus, and

thence a quadrans or semi-obolus, by which it is easy to distinguish if,

and in what degree, that metal is adulterated. All these stones are

found in the River Tmolus; their texture is smooth and like that of

pebbles; their figure broad, not round; and their bigness twice that of

the common larger sort of pebbles. In their use in the trial of metals

there is a difference in power between their upper surface, which has

lain toward the sun, and their under, which has been to the earth; the

upper performing its office the more nicely; and this is consonant to

reason, as the upper part is dryer; for the humidity of the other

surface hinders its receiving so well the particles of metals; for the

same reason also it does not perform its office as well in hot weather

as in colder, for in the hot it emits a kind of humidity out of its

substance, which runs all over it. This hinders the metalline particles

from adhering perfectly, and makes mistakes in the trials. This

exudation of a humid matter is also common to many other stones, among

others, to those of which statues are made; and this has been looked on

as peculiar to the statue." (Based on Hill's trans.) This humid

"exudation of fine-grained stones in summer" would not sound abnormal if

it were called condensation. Pliny (XXXIII, 43) says: "The mention of

gold and silver should be accompanied by that of the stone called

_coticula_. Formerly, according to Theophrastus, it was only to be found

in the river Tmolus but now found in many parts, it was found in small

pieces never over four inches long by two broad. That side which lay

toward the sun is better than that toward the ground. Those experienced

with the _coticula_ when they rub ore (_vena_) with it, can at once say

how much gold it contains, how much silver or copper. This method is so

accurate that they do not mistake it to a scruple." This purported use

for determining values of _ore_ is of about Pliny's average accuracy.

The first detailed account of touch-needles and their manner of making,

which we have been able to find, is that of the _Probierbuechlein_ (1527?

see Appendix) where many of the tables given by Agricola may be found.

[38] _De Natura Fossilium_ (p. 267) and _De Ortu et Causis

Subterraneorum_ (p. 59). The author does not add any material

mineralogical information to the quotations from Theophrastus and Pliny

given above.

[39] In these tables Agricola has simply adopted Roman names as

equivalents of the old German weights, but as they did not always

approximate in proportions, he coined terms such as "units of 4

_siliquae_," etc. It might seem more desirable to have introduced the

German terms into this text, but while it would apply in this instance,

as we have discussed on p. 259, the actual values of the Roman weights

are very different from the German, and as elsewhere in the book actual

Roman weights are applied, we have considered it better to use the Latin

terms consistently throughout. Further, the obsolete German would be to

most readers but little improvement upon the Latin. For convenience of

readers we set out the various scales as used by Agricola, together with

the German:--

ROMAN SCALE. OLD GERMAN SCALE.

6 _Siliquae_ = 1 _Scripulum_ 3 _Grenlin_ = 1 _Gran_

4 _Scripula_ = 1 _Sextula_ 4 _Gran_ = 1 _Krat_

2 _Sextulae_ = 1 _Duella_ 24 _Kratt_ = 1 _Mark_

24 _Duellae_ = 1 _Bes_ or

24 _Grenlin_ = 1 "_Nummus_"

12 "_Nummi_" = 1 _Mark_

Also the following scales are applied to fineness by Agricola:--

3 _Scripula_ = 1 _Drachma_ 4 _Pfennige_ = 1 _Quintlein_

2 _Drachmae_ = 1 _Sicilicus_ 4 _Quintlein_ = 1 _Loth_

2 _Sicilici_ = 1 _Semuncia_ 16 _Loth_ = 1 _Mark_

16 _Semunciae_ = 1 _Bes_

The term "_nummus_," a coin, given above and in the text, appears in the

German translation as _pfennig_ as applied to both German scales, but as

they are of different values, we have left Agricola's adaptation in one

scale to avoid confusion. The Latin terms adopted by Agricola are given

below, together with the German:--

Number in one Value in

Roman Term. German Term. Mark or Bes. _Siliquae_.

_Siliqua_ 1152 1

"Unit of 4 _Siliquae_" _Grenlin_ 288 4

_Pfennig_ 256 --

_Scripulum_ _Scruple_ (?) 192 6

_Semi-sextula_ _Gran_ 96 12

_Drachma_ _Quintlein_ 64 18

_Sextula_ _Halb Krat_ 48 24

_Sicilicus_ _Halb Loth_ 32 36

_Duella_ _Krat_ 24 48

_Semuncia_ _Loth_ 16 72

"_Unit of 5 Drachmae "_Nummus_" 12 96

& 1 Scripulum_"

_Uncia_ _Untzen_ 8 144

_Bes_ _Mark_ 1 1152

While the proportions in a _bes_ or _mark_ are the same in both scales,

the actual weight values are vastly different--for instance, the _mark_

contained about 3609.6, and the _bes_ 3297 Troy Grains. Agricola also

uses:

_Selibra_ _Halb-pfundt_

_Libra_ _Pfundt_

_Centumpondium_ _Centner_.

As the Roman _libra_ contains 12 _unciae_ and the German _pfundt_ 16

_untzen_, the actual weights of these latter quantities are still

further apart--the former 4946 and the latter 7219 Troy grains.

[40] There are no tables in the Latin text, the whole having been

written out _in extenso_, but they have now been arranged as above, as

being in a much more convenient and expressive form.

[41] See note 39 above.

[42] See note 27, p. 242, for discussion of this "Assay ton"

arrangement.

[43] _Agrippinenses_ and _Antuerpiani_.

BOOK VIII.

Questions of assaying were explained in the last Book, and I have now

come to a greater task, that is, to the description of how we extract

the metals. First of all I will explain the method of preparing the

ore[1]; for since Nature usually creates metals in an impure state,

mixed with earth, stones, and solidified juices, it is necessary to

separate most of these impurities from the ores as far as can be, before

they are smelted, and therefore I will now describe the methods by which

the ores are sorted, broken with hammers, burnt, crushed with stamps,

ground into powder, sifted, washed, roasted, and calcined[2].

I will start at the beginning with the first sort of work. Experienced

miners, when they dig the ore, sort the metalliferous material from

earth, stones, and solidified juices before it is taken from the shafts

and tunnels, and they put the valuable metal in trays and the waste into

buckets. But if some miner who is inexperienced in mining matters has

omitted to do this, or even if some experienced miner, compelled by some

unavoidable necessity, has been unable to do so, as soon as the material

which has been dug out has been removed from the mine, all of it should

be examined, and that part of the ore which is rich in metal sorted from

that part of it which is devoid of metal, whether such part be earth, or

solidified juices, or stones. To smelt waste together with an ore

involves a loss, for some expenditure is thrown away, seeing that out of

earth and stones only empty and useless slags are melted out, and

further, the solidified juices also impede the smelting of the metals

and cause loss. The rock which lies contiguous to rich ore should also

be broken into small pieces, crushed, and washed, lest any of the

mineral should be lost. When, either through ignorance or carelessness,

the miners while excavating have mixed the ore with earth or broken

rock, the work of sorting the crude metal or the best ore is done not

only by men, but also by boys and women. They throw the mixed material

upon a long table, beside which they sit for almost the whole day, and

they sort out the ore; when it has been sorted out, they collect it in

trays, and when collected they throw it into tubs, which are carried to

the works in which the ores are smelted.

[Illustration 268 (Sorting Ore): A--Long table. B--Tray. C--Tub.]

[Illustration 269 (Cutting Metal): A--Masses of metal. B--Hammer.

C--Chisel. D--Tree stumps. E--Iron tool similar to a pair of shears.]

The metal which is dug out in a pure or crude state, to which class

belong native silver, silver glance, and gray silver, is placed on a

stone by the mine foreman and flattened out by pounding with heavy

square hammers. These masses, when they have been thus flattened out

like plates, are placed either on the stump of a tree, and cut into

pieces by pounding an iron chisel into them with a hammer, or else they

are cut with an iron tool similar to a pair of shears. One blade of

these shears is three feet long, and is firmly fixed in a stump, and the

other blade which cuts the metal is six feet long. These pieces of

metal are afterward heated in iron basins and smelted in the cupellation

furnace by the smelters.

[Illustration 270 (Spalling Ore): A--Tables. B--Upright planks.

C--Hammer. D--Quadrangular hammer. E--Deeper vessel. F--Shallower

vessel. G--Iron rod.]

Although the miners, in the shafts or tunnels, have sorted over the

material which they mine, still the ore which has been broken down and

carried out must be broken into pieces by a hammer or minutely crushed,

so that the more valuable and better parts can be distinguished from the

inferior and worthless portions. This is of the greatest importance in

smelting ore, for if the ore is smelted without this separation, the

valuable part frequently receives great damage before the worthless part

melts in the fire, or else the one consumes the other; this latter

difficulty can, however, be partly avoided by the exercise of care and

partly by the use of fluxes. Now, if a vein is of poor quality, the

better portions which have been broken down and carried out should be

thrown together in one place, and the inferior portion and the rock

thrown away. The sorters place a hard broad stone on a table; the tables

are generally four feet square and made of joined planks, and to the

edge of the sides and back are fixed upright planks, which rise about a

foot from the table; the front, where the sorter sits, is left open. The

lumps of ore, rich in gold or silver, are put by the sorters on the

stone and broken up with a broad, but not thick, hammer; they either

break them into pieces and throw them into one vessel, or they break and

sort--whence they get their name--the more precious from the worthless,

throwing and collecting them separately into different vessels. Other

men crush the lumps of ore less rich in gold or silver, which have

likewise been put on the stone, with a broad thick hammer, and when it

has been well crushed, they collect it and throw it into one vessel.

There are two kinds of vessels; one is deeper, and a little wider in the

centre than at the top or bottom; the other is not so deep though it is

broader at the bottom, and becomes gradually a little narrower toward

the top. The latter vessel is covered with a lid, while the former is

not covered; an iron rod through the handles, bent over on either end,

is grasped in the hand when the vessel is carried. But, above all, it

behooves the sorters to be assiduous in their labours.

[Illustration 271 (Spalling Ore): A--Pyrites. B--Leggings. C--Gloves.

D--Hammer.]

By another method of breaking ore with hammers, large hard fragments of

ore are broken before they are burned. The legs of the workmen--at all

events of those who crush pyrites in this manner with large hammers in

Goslar--are protected with coverings resembling leggings, and their

hands are protected with long gloves, to prevent them from being

injured by the chips which fly away from the fragments.

[Illustration 272 (Spalling Ore): A--Area paved with stones. B--Broken

ore. C--Area covered with broken ore. D--Iron tool. E--Its handle.

F--Broom. G--Short strake. H--Wooden hoe.]

In that district of Greater Germany which is called Westphalia and in

that district of Lower Germany which is named Eifel, the broken ore

which has been burned, is thrown by the workmen into a round area paved

with the hardest stones, and the fragments are pounded up with iron

tools, which are very much like hammers in shape and are used like

threshing sledges. This tool is a foot long, a palm wide, and a digit

thick, and has an opening in the middle just as hammers have, in which

is fixed a wooden handle of no great thickness, but up to three and a

half feet long, in order that the workmen can pound the ore with greater

force by reason of its weight falling from a greater height. They strike

and pound with the broad side of the tool, in the same way as corn is

pounded out on a threshing floor with the threshing sledges, although

the latter are made of wood and are smooth and fixed to poles. When the

ore has been broken into small pieces, they sweep it together with

brooms and remove it to the works, where it is washed in a short

strake, at the head of which stands the washer, who draws the water

upward with a wooden hoe. The water running down again, carries all the

light particles into a trough placed underneath. I shall deal more fully

with this method of washing a little later.

Ore is burned for two reasons; either that from being hard, it may

become soft and more easily broken and more readily crushed with a

hammer or stamps, and then can be smelted; or that the fatty things,

that is to say, sulphur, bitumen, orpiment, or realgar[3] may be

consumed. Sulphur is frequently found in metallic ores, and, generally

speaking, is more harmful to the metals, except gold, than are the other

things. It is most harmful of all to iron, and less to tin than to

bismuth, lead, silver, or copper. Since very rarely gold is found in

which there is not some silver, even gold ores containing sulphur ought

to be roasted before they are smelted, because, in a very vigorous

furnace fire, sulphur resolves metal into ashes and makes slag of it.

Bitumen acts in the same way, in fact sometimes it consumes silver,

which we may see in bituminous _cadmia_[4].

[Illustration 274 (Stall Roasting Ore): A--Area. B--Wood. C--Ore.

D--Cone-shaped piles. E--Canal.]

I now come to the methods of roasting, and first of all to that one

which is common to all ores. The earth is dug out to the required

extent, and thus is made a quadrangular area of fair size, open at the

front, and above this, firewood is laid close together, and on it other

wood is laid transversely, likewise close together, for which reason our

countrymen call this pile of wood a crate; this is repeated until the

pile attains a height of one or two cubits. Then there is placed upon it

a quantity of ore that has been broken into small pieces with a hammer;

first the largest of these pieces, next those of medium size, and lastly

the smallest, and thus is built up a gently sloping cone. To prevent it

from becoming scattered, fine sand of the same ore is soaked with water

and smeared over it and beaten on with shovels; some workers, if they

cannot obtain such fine sand, cover the pile with charcoal-dust, just as

do charcoal-burners. But at Goslar, the pile, when it has been built up

in the form of a cone, is smeared with _atramentum sutorium rubrum_[5],

which is made by the leaching of roasted pyrites soaked with water. In

some districts the ore is roasted once, in others twice, in others three

times, as its hardness may require. At Goslar, when pyrites is roasted

for the third time, that which is placed on the top of the pyre exudes a

certain greenish, dry, rough, thin substance, as I have elsewhere

written[6]; this is no more easily burned by the fire than is asbestos.

Very often also, water is put on to the ore which has been roasted,

while it is still hot, in order to make it softer and more easily

broken; for after fire has dried up the moisture in the ore, it breaks

up more easily while it is still hot, of which fact burnt limestone

affords the best example.

[Illustration 275 (Heap Roasting Ore): A--Lighted pyre. B--Pyre which is

being constructed. C--Ore. D--Wood. E--Pile of the same wood.]

By digging out the earth they make the areas much larger, and square;

walls should be built along the sides and back to hold the heat of the

fire more effectively, and the front should be left open. In these

compartments tin ore is roasted in the following manner. First of all

wood about twelve feet long should be laid in the area in four layers,

alternately straight and transverse. Then the larger pieces of ore

should be laid upon them, and on these again the smaller ones, which

should also be placed around the sides; the fine sand of the same ore

should also be spread over the pile and pounded with shovels, to prevent

the pile from falling before it has been roasted; the wood should then

be fired.

[Illustration 276 (Stall Roasting Ore): A--Burning pyre which is

composed of lead ore with wood placed above it. B--Workman throwing ore

into another area. C--Oven-shaped furnace. D--Openings through which the

smoke escapes.]

Lead ore, if roasting is necessary, should be piled in an area just like

the last, but sloping, and the wood should be placed over it. A tree

trunk should be laid right across the front of the ore to prevent it

from falling out. The ore, being roasted in this way, becomes partly

melted and resembles slag. Thuringian pyrites, in which there is gold,

sulphur, and vitriol, after the last particle of vitriol has been

obtained by heating it in water, is thrown into a furnace, in which logs

are placed. This furnace is very similar to an oven in shape, in order

that when the ore is roasted the valuable contents may not fly away with

the smoke, but may adhere to the roof of the furnace. In this way

sulphur very often hangs like icicles from the two openings of the roof

through which the smoke escapes.

[Illustration 277 (Hearths for roasting): A--Iron plates full of holes.

B--Walls. C--Plate on which ore is placed. D--Burning charcoal placed on

the ore. E--Pots. F--Furnace. G--Middle part of upper chamber. H--The

other two compartments. I--Divisions of the lower chamber. K--Middle

wall. L--Pots which are filled with ore. M--Lids of same pots.

N--Grating.]

If pyrites or _cadmia_, or any other ore containing metal, possesses a

good deal of sulphur or bitumen, it should be so roasted that neither is

lost. For this purpose it is thrown on an iron plate full of holes, and

roasted with charcoal placed on top; three walls support this plate, two

on the sides and the third at the back. Beneath the plate are placed

pots containing water, into which the sulphurous or bituminous vapour

descends, and in the water the fat accumulates and floats on the top. If

it is sulphur, it is generally of a yellow colour; if bitumen, it is

black like pitch. If these were not drawn out they would do much harm to

the metal, when the ore is being smelted. When they have thus been

separated they prove of some service to man, especially the sulphurous

kind. From the vapour which is carried down, not into the water, but

into the ground, there is created a sulphurous or a bituminous substance

resembling _pompholyx_[7], and so light that it can be blown away with a

breath. Some employ a vaulted furnace, open at the front and divided

into two chambers. A wall built in the middle of the furnace divides the

lower chamber into two equal parts, in which are set pots containing

water, as above described. The upper chamber is again divided into three

parts, the middle one of which is always open, for in it the wood is

placed, and it is not broader than the middle wall, of which it forms

the topmost portion. The other two compartments have iron doors which

are closed, and which, together with the roof, keep in the heat when the

wood is lighted. In these upper compartments are iron bars which take

the place of a floor, and on these are arranged pots without bottoms,

having in place of a bottom, a grating made of iron wire, fixed to each,

through the openings of which the sulphurous or bituminous vapours

roasted from the ore run into the lower pots. Each of the upper pots

holds a hundred pounds of ore; when they are filled they are covered

with lids and smeared with lute.

[Illustration 278 (Heap Roasting): A--Heap of cupriferous stones.

B--Kindled heap. C--Stones being taken to the beds of faggots.]

In Eisleben and the neighbourhood, when they roast the schistose stone

from which copper is smelted, and which is not free from bitumen, they

do not use piles of logs, but bundles of faggots. At one time, they used

to pile this kind of stone, when extracted from the pit, on bundles of

faggots and roast it by firing the faggots; nowadays, they first of all

carry these same stones to a heap, where they are left to lie for some

time in such a way as to allow the air and rain to soften them. Then

they make a bed of faggot bundles near the heap, and carry the nearest

stones to this bed; afterward they again place bundles of faggots in the

empty place from which the first stones have been removed, and pile over

this extended bed, the stones which lay nearest to the first lot; and

they do this right up to the end, until all the stones have been piled

mound-shape on a bed of faggots. Finally they fire the faggots, not,

however, on the side where the wind is blowing, but on the opposite

side, lest the fire blown up by the force of the wind should consume the

faggots before the stones are roasted and made soft; by this method the

stones which are adjacent to the faggots take fire and communicate it to

the next ones, and these again to the adjoining ones, and in this way

the heap very often burns continuously for thirty days or more. This

schist rock when rich in copper, as I have said elsewhere, exudes a

substance of a nature similar to asbestos.

[Illustration 284 (Stamp-mill): A--Mortar. B--Upright posts.

C--Cross-beams. D--Stamps. E--Their heads. F--Axle (cam-shaft). G--Tooth

of the stamp (tappet). H--Teeth of axle (cams).]

Ore is crushed with iron-shod stamps, in order that the metal may be

separated from the stone and the hangingwall rock.[8] The machines which

miners use for this purpose are of four kinds, and are made by the

following method. A block of oak timber six feet long, two feet and a

palm square, is laid on the ground. In the middle of this is fixed a

mortar-box, two feet and six digits long, one foot and six digits deep;

the front, which might be called a mouth, lies open; the bottom is

covered with a plate of iron, a palm thick and two palms and as many

digits wide, each end of which is wedged into the timber with broad

wedges, and the front and back part of it are fixed to the timber with

iron nails. To the sides of the mortar above the block are fixed two

upright posts, whose upper ends are somewhat cut back and are mortised

to the timbers of the building. Two and a half feet above the mortar

are placed two cross-beams joined together, one in front and one in the

back, the ends of which are mortised into the upright posts already

mentioned. Through each mortise is bored a hole, into which is driven an

iron clavis; one end of the clavis has two horns, and the other end is

perforated in order that a wedge driven through, binds the beams more

firmly; one horn of the clavis turns up and the other down. Three and a

half feet above the cross-beams, two other cross-beams of the same kind

are again joined in a similar manner; these cross-beams have square

openings, in which the iron-shod stamps are inserted. The stamps are not

far distant from each other, and fit closely in the cross-beams. Each

stamp has a tappet at the back, which requires to be daubed with grease

on the lower side that it can be raised more easily. For each stamp

there are on a cam-shaft, two cams, rounded on the outer end, which

alternately raise the stamp, in order that, by its dropping into the

mortar, it may with its iron head pound and crush the rock which has

been thrown under it. To the cam-shaft is fixed a water-wheel whose

buckets are turned by water-power. Instead of doors, the mouth of the

mortar has a board, which is fitted into notches cut out of the front of

the block. This board can be raised, in order that when the mouth is

open, the workmen can remove with a shovel the fine sand, and likewise

the coarse sand and broken rock, into which the rocks have been crushed;

this board can be lowered, so that the mouth thus being closed, the

fresh rock thrown in may be crushed with the iron-shod stamps. If an oak

block is not available, two timbers are placed on the ground and joined

together with iron clamps, each of the timbers being six feet long, a

foot wide, and a foot and a half thick. Such depth as should be allowed

to the mortar, is obtained by cutting out the first beam to a width of

three-quarters of a foot and to a length of two and a third and one

twenty-fourth of a foot. In the bottom of the part thus dug out, there

should be laid a very hard rock, a foot thick and three-quarters of a

foot wide; about it, if any space remains, earth or sand should be

filled in and pounded. On the front, this bed rock is covered with a

plank; this rock when it has been broken, should be taken away and

replaced by another. A smaller mortar having room for only three stamps

may also be made in the same manner.

[Illustration 285 (Stamps): A--Stamp. B--Stem cut out in lower part.

C--Shoe. D--The other shoe, barbed and grooved. E--Quadrangular iron

band. F--Wedge. G--Tappet. H--Angular cam-shaft. I--Cams. K--Pair of

compasses.]

The stamp-stems are made of small square timbers nine feet long and half

a foot wide each way. The iron head of each is made in the following

way; the lower part of the head is three palms long and the upper part

the same length. The lower part is a palm square in the middle for two

palms, then below this, for a length of two digits it gradually spreads

until it becomes five digits square; above the middle part, for a length

of two digits, it again gradually swells out until it becomes a palm and

a half square. Higher up, where the head of the shoe is enclosed in the

stem, it is bored through and similarly the stem itself is pierced, and

through the opening of each, there passes a broad iron wedge, which

prevents the head falling off the stem. To prevent the stamp head from

becoming broken by the constant striking of fragments of ore or rocks,

there is placed around it a quadrangular iron band a digit thick, seven

digits wide, and six digits deep. Those who use three stamps, as is

common, make them much larger, and they are made square and three palms

broad each way; then the iron shoe of each has a total length of two

feet and a palm; at the lower end, it is hexagonal, and at that point it

is seven digits wide and thick. The lower part of it which projects

beyond the stem is one foot and two palms long; the upper part, which is

enclosed in the stem, is three palms long; the lower part is a palm

wide and thick; then gradually the upper part becomes narrower and

thinner, so that at the top it is three digits and a half wide and two

thick. It is bored through at the place where the angles have been

somewhat cut away; the hole is three digits long and one wide, and is

one digit's distance from the top. There are some who make that part of

the head which is enclosed in the stem, barbed and grooved, in order

that when the hooks have been fixed into the stem and wedges fitted to

the grooves, it may remain tightly fixed, especially when it is also

held with two quadrangular iron bands. Some divide the cam-shaft with a

compass into six sides, others into nine; it is better for it to be

divided into twelve sides, in order that successively one side may

contain a cam and the next be without one.

[Illustration 286 (Stamp-mill): A--Box. Although the upper part is not

open, it is shown open here, that the wheel may be seen. B--Wheel.

C--Cam-shaft. D--Stamps.]

The water-wheel is entirely enclosed under a quadrangular box, in case

either the deep snows or ice in winter, or storms, may impede its

running and its turning around. The joints in the planks are stopped all

around with moss. The cover, however, has one opening, through which

there passes a race bringing down water which, dropping on the buckets

of the wheel, turns it round, and flows out again in the lower race

under the box. The spokes of the water-wheel are not infrequently

mortised into the middle of the cam-shaft; in this case the cams on

both sides raise the stamps, which either both crush dry or wet ore, or

else the one set crushes dry ore and the other set wet ore, just as

circumstances require the one or the other; further, when the one set is

raised and the iron clavises in them are fixed into openings in the

first cross-beam, the other set alone crushes the ore.

[Illustration 287 (Handling stamped material): A--Box laid flat on the

ground. B--Its bottom which is made of iron wire. C--Box inverted.

D--Iron rods. E--Box suspended from a beam, the inside being visible.

F--Box suspended from a beam, the outside being visible.]

Broken rock or stones, or the coarse or fine sand, are removed from the

mortar of this machine and heaped up, as is also done with the same

materials when raked out of the dump near the mine. They are thrown by a

workman into a box, which is open on the top and the front, and is three

feet long and nearly a foot and a half wide. Its sides are sloping and

made of planks, but its bottom is made of iron wire netting, and

fastened with wire to two iron rods, which are fixed to the two side

planks. This bottom has openings, through which broken rock of the size

of a hazel nut cannot pass; the pieces which are too large to pass

through are removed by the workman, who again places them under stamps,

while those which have passed through, together with the coarse and fine

sand, he collects in a large vessel and keeps for the washing. When he

is performing his laborious task he suspends the box from a beam by two

ropes. This box may rightly be called a quadrangular sieve, as may also

that kind which follows.

[Illustration 288 (Sifting Ore): A--Sieve. B--Small planks. C--Post.

D--Bottom of sieve. E--Open box. F--Small cross-beam. G--Upright posts.]

Some employ a sieve shaped like a wooden bucket, bound with two iron

hoops; its bottom, like that of the box, is made of iron wire netting.

They place this on two small cross-planks fixed upon a post set in the

ground. Some do not fix the post in the ground, but stand it on the

ground until there arises a heap of the material which has passed

through the sieve, and in this the post is fixed. With an iron shovel

the workman throws into this sieve broken rock, small stones, coarse and

fine sand raked out of the dump; holding the handles of the sieve in his

hands, he agitates it up and down in order that by this movement the

dust, fine and coarse sand, small stones, and fine broken rock may fall

through the bottom. Others do not use a sieve, but an open box, whose

bottom is likewise covered with wire netting; this they fix on a small

cross-beam fastened to two upright beams and tilt it backward and

forward.

[Illustration 289 (Sifting Ore): A--Box. B--Bale. C--Rope. D--Beam.

E--Handles. F--Five-toothed rake. G--Sieve. H--Its handles. I--Pole.

K--Rope. L--Timber.]

Some use a sieve made of copper, having square copper handles on both

sides, and through these handles runs a pole, of which one end projects

three-quarters of a foot beyond one handle; the workman then places that

end in a rope which is suspended from a beam, and rapidly shakes the

pole alternately backward and forward. By this movement the small

particles fall through the bottom of the sieve. In order that the end of

the pole may be easily placed in the rope, a stick, two palms long,

holds open the lower part of the rope as it hangs double, each end of

the rope being tied to the beam; part of the rope, however, hangs beyond

the stick to a length of half a foot. A large box is also used for this

purpose, of which the bottom is either made of a plank full of holes or

of iron netting, as are the other boxes. An iron bale is fastened from

the middle of the planks which form its sides; to this bale is fastened

a rope which is suspended from a wooden beam, in order that the box may

be moved or tilted in any direction. There are two handles on each end,

not unlike the handles of a wheelbarrow; these are held by two workmen,

who shake the box to and fro. This box is the one principally used by

the Germans who dwell in the Carpathian mountains. The smaller particles

are separated from the larger ones by means of three boxes and two

sieves, in order that those which pass through each, being of equal

size, may be washed together; for the bottoms of both the boxes and

sieves have openings which do not let through broken rock of the size of

a hazel nut. As for the dry remnants in the bottoms of the sieves, if

they contain any metal the miners put them under the stamps. The larger

pieces of broken rock are not separated from the smaller by this method

until the men and boys, with five-toothed rakes, have separated them

from the rock fragments, the little stones, the coarse and the fine sand

and earth, which have been thrown on to the dumps.

[Illustration 291 (Sifting Ore): A--Workman carrying broken rock in a

barrow. B--First chute. C--First box. D--Its handles. E--Its bales.

F--Rope. G--Beam. H--Post. I--Second chute. K--Second box. L--Third

chute. M--Third box. N--First table. O--First sieve. P--First tub.

Q--Second table. R--Second sieve. S--Second tub. T--Third table.

V--Third sieve. X--Third tub. Y--Plugs.]

At Neusohl, in the Carpathians, there are mines where the veins of

copper lie in the ridges and peaks of the mountains, and in order to

save expense being incurred by a long and difficult transport, along a

rough and sometimes very precipitous road, one workman sorts over the

dumps which have been thrown out from the mines, and another carries in

a wheelbarrow the earth, fine and coarse sand, little stones, broken

rock, and even the poorer ore, and overturns the barrow into a long open

chute fixed to a steep rock. This chute is held apart by small cleats,

and the material slides down a distance of about one hundred and fifty

feet into a short box, whose bottom is made of a thick copper plate,

full of holes. This box has two handles by which it is shaken to and

fro, and at the top there are two bales made of hazel sticks, in which

is fixed the iron hook of a rope hung from the branch of a tree or from

a wooden beam which projects from an upright post. From time to time a

sifter pulls this box and thrusts it violently against the tree or post,

by which means the small particles passing through its holes descend

down another chute into another short box, in whose bottom there are

smaller holes. A second sifter, in like manner, thrusts this box

violently against a tree or post, and a second time the smaller

particles are received into a third chute, and slide down into a third

box, whose bottom has still smaller holes. A third sifter, in like

manner, thrusts this box violently against a tree or post, and for the

third time the tiny particles fall through the holes upon a table. While

the workman is bringing in the barrow, another load which has been

sorted from the dump, each sifter withdraws the hooks from his bale and

carries away his own box and overturns it, heaping up the broken rock or

sand which remains in the bottom of it. As for the tiny particles which

have slid down upon the table, the first washer--for there are as many

washers as sifters--sweeps them off and in a tub nearly full of water,

washes them through a sieve whose holes are smaller than the holes of

the third box. When this tub has been filled with the material which has

passed through the sieve, he draws out the plug to let the water run

away; then he removes with a shovel that which has settled in the tub

and throws it upon the table of a second washer, who washes it in a

sieve with smaller holes. The sediment which has this time settled in

his tub, he takes out and throws on the table of a third washer, who

washes it in a sieve with the smallest holes. The copper concentrates

which have settled in the last tub are taken out and smelted; the

sediment which each washer has removed with a limp is washed on a canvas

strake. The sifters at Altenberg, in the tin mines of the mountains

bordering on Bohemia, use such boxes as I have described, hung from

wooden beams. These, however, are a little larger and open in the front,

through which opening the broken rock which has not gone through the

sieve can be shaken out immediately by thrusting the sieve against its

post.

[Illustration 292 (Sifting Ore): A--Sieve. B--Its handles. C--Tub.

D--Bottom of sieve made of iron wires. E--Hoop. F--Rods. G--Hoops.

H--Woman shaking the sieve. I--Boy supplying it with material which

requires washing. K--Man with shovel removing from the tub the material

which has passed through the sieve.]

If the ore is rich in metal, the earth, the fine and coarse sand, and

the pieces of rock which have been broken from the hangingwall, are dug

out of the dump with a spade or rake and, with a shovel, are thrown into

a large sieve or basket, and washed in a tub nearly full of water. The

sieve is generally a cubit broad and half a foot deep; its bottom has

holes of such size that the larger pieces of broken rock cannot pass

through them, for this material rests upon the straight and cross iron

wires, which at their points of contact are bound by small iron clips.

The sieve is held together by an iron band and by two cross-rods

likewise of iron; the rest of the sieve is made of staves in the shape

of a little tub, and is bound with two iron hoops; some, however, bind

it with hoops of hazel or oak, but in that case they use three of them.

On each side it has handles, which are held in the hands by whoever

washes the metalliferous material. Into this sieve a boy throws the

material to be washed, and a woman shakes it up and down, turning it

alternately to the right and to the left, and in this way passes

through it the smaller pieces of earth, sand, and broken rock. The

larger pieces remain in the sieve, and these are taken out, placed in a

heap and put under the stamps. The mud, together with fine sand, coarse

sand, and broken rock, which remain after the water has been drawn out

of the tub, is removed by an iron shovel and washed in the sluice, about

which I will speak a little later.

[Illustration 293 (Sifting Ore): A--Basket. B--Its handles. C--Dish.

D--Its back part. E--Its front part. F--Handles of same.]

The Bohemians use a basket a foot and a half broad and half a foot deep,

bound together by osiers. It has two handles by which it is grasped,

when they move it about and shake it in the tub or in a small pool

nearly full of water. All that passes through it into the tub or pool

they take out and wash in a bowl, which is higher in the back part and

lower and flat in the front; it is grasped by the two handles and shaken

in the water, the lighter particles flowing away, and the heavier and

mineral portion sinking to the bottom.

[Illustration 294 (Mills for Grinding Ore): A--Axle. B--Water-wheel.

C--Toothed drum. D--Drum made of rundles. E--Iron axle. F--Millstone.

G--Hopper. H--Round wooden plate. I--Trough.]

Gold ore, after being broken with hammers or crushed by the stamps, and

even tin ore, is further milled to powder. The upper millstone, which

is turned by water-power, is made in the following way. An axle is

rounded to compass measure, or is made angular, and its iron pinions

turn in iron sockets which are held in beams. The axle is turned by a

water-wheel, the buckets of which are fixed to the rim and are struck by

the force of a stream. Into the axle is mortised a toothed drum, whose

teeth are fixed in the side of the rim. These teeth turn a second drum

of rundles, which are made of very hard material. This drum surrounds an

iron axle which has a pinion at the bottom and revolves in an iron cup

in a timber. At the top of the iron axle is an iron tongue, dove-tailed

into the millstone, and so when the teeth of the one drum turn the

rundles of the other, the millstone is made to turn round. An

overhanging machine supplies it with ore through a hopper, and the ore,

being ground to powder, is discharged from a round wooden plate into a

trough and flowing away through it accumulates on the floor; from there

the ore is carried away and reserved for washing. Since this method of

grinding requires the millstone to be now raised and now lowered, the

timber in whose socket the iron of the pinion axle revolves, rests upon

two beams, which can be raised and lowered.

[Illustration 296 (Mills for Grinding Ore): A--First mill. B--Wheel

turned by goats. C--Second mill. D--Disc of upright axle. E--Its toothed

drum. F--Third mill. G--Shape of lower millstone. H--Small upright axle

of the same. I--Its opening. K--Lever of the upper millstone. L--Its

opening.]

There are three mills in use in milling gold ores, especially for

quartz[11] which is not lacking in metal. They are not all turned by

water-power, but some by the strength of men, and two of them even by

the power of beasts of burden. The first revolving one differs from the

next only in its driving wheel, which is closed in and turned by men

treading it, or by horses, which are placed inside, or by asses, or even

by strong goats; the eyes of these beasts are covered by linen bands.

The second mill, both when pushed and turned round, differs from the two

above by having an upright axle in the place of the horizontal one; this

axle has at its lower end a disc, which two workmen turn by treading

back its cleats with their feet, though frequently one man sustains all

the labour; or sometimes there projects from the axle a pole which is

turned by a horse or an ass, for which reason it is called an

_asinaria_. The toothed drum which is at the upper end of the axle turns

the drum which is made of rundles, and together with it the millstone.

The third mill is turned round and round, and not pushed by hand; but

between this and the others there is a great distinction, for the lower

millstone is so shaped at the top that it can hold within it the upper

millstone, which revolves around an iron axle; this axle is fastened in

the centre of the lower stone and passes through the upper stone. A

workman, by grasping in his hand an upright iron bar placed in the upper

millstone, moves it round. The middle of the upper millstone is bored

through, and the ore, being thrown into this opening, falls down upon

the lower millstone and is there ground to powder, which gradually runs

out through its opening; it is washed by various methods before it is

mixed with quicksilver, which I will explain presently.

[Illustration 299 (Stamp-mill): A--Water-wheel. B--Axle. C--Stamp.

D--Hopper in the upper millstone. E--Opening passing through the centre.

F--Lower millstone. G--Its round depression. H--Its outlet. I--Iron

axle. K--Its crosspiece. L--Beam. M--Drum of rundles on the iron axle.

N--Toothed drum of main axle. O--Tubs. P--The small planks. Q--Small

upright axles. R--Enlarged part of one. S--Their paddles. T--Their drums

which are made of rundles. V--Small horizontal axle set into the end of

the main axle. X--Its toothed drums. Y--Three sluices. Z--Their small

axles. AA--Spokes. BB--Paddles.]

Some people build a machine which at one and the same time can crush,

grind, cleanse, and wash the gold ore, and mix the gold with

quicksilver. This machine has one water-wheel, which is turned by a

stream striking its buckets; the main axle on one side of the

water-wheel has long cams, which raise the stamps that crush the dry

ore. Then the crushed ore is thrown into the hopper of the upper

millstone, and gradually falling through the opening, is ground to

powder. The lower millstone is square, but has a round depression in

which the round, upper millstone turns, and it has an outlet from which

the powder falls into the first tub. A vertical iron axle is dove-tailed

into a cross-piece, which is in turn fixed into the upper millstone; the

upper pinion of this axle is held in a bearing fixed in a beam; the drum

of the vertical axle is made of rundles, and is turned by the toothed

drum on the main axle, and thus turns the millstone. The powder falls

continually into the first tub, together with water, and from there runs

into a second tub which is set lower down, and out of the second into a

third, which is the lowest; from the third, it generally flows into a

small trough hewn out of a tree trunk. Quicksilver[12] is placed in

each tub, across which is fixed a small plank, and through a hole in the

middle of each plank there passes a small upright axle, which is

enlarged above the plank to prevent it from dropping into the tub lower

than it should. At the lower end of the axle three sets of paddles

intersect, each made from two little boards fixed to the axle opposite

each other. The upper end of this axle has a pinion held by a bearing

set in a beam, and around each of these axles is a small drum made of

rundles, each of which is turned by a small toothed drum on a horizontal

axle, one end of which is mortised into the large horizontal axle, and

the other end is held in a hollow covered with thick iron plates in a

beam. Thus the paddles, of which there are three sets in each tub, turn

round, and agitating the powder, thoroughly mix it with water and

separate the minute particles of gold from it, and these are attracted

by the quicksilver and purified. The water carries away the waste. The

quicksilver is poured into a bag made of leather or cloth woven from

cotton, and when this bag is squeezed, as I have described elsewhere,

the quicksilver drips through it into a jar placed underneath. The pure

gold[13] remains in the bag. Some people substitute three broad sluices

for the tubs, each of which has an angular axle on which are set six

narrow spokes, and to them are fixed the same number of broad paddles;

the water that is poured in strikes these paddles and turns them round,

and they agitate the powder which is mixed with the water and separate

the metal from it. If the powder which is being treated contains gold

particles, the first method of washing is far superior, because the

quicksilver in the tubs immediately attracts the gold; if it is powder

in which are the small black stones from which tin is smelted, this

latter method is not to be despised. It is very advantageous to place

interlaced fir boughs in the sluices in which such tin-stuff is washed,

after it has run through the launders from the mills, because the fine

tin-stone is either held back by the twigs, or if the current carries

them along they fall away from the water and settle down.

Seven methods of washing are in common use for the ores of many metals;

for they are washed either in a simple buddle, or in a divided buddle,

or in an ordinary strake, or in a large tank, or in a short strake, or

in a canvas strake, or in a jigging sieve. Other methods of washing are

either peculiar to some particular metal, or are combined with the

method of crushing wet ore by stamps.

[Illustration 301 (Buddles): A--Head of buddle. B--Pipe. C--Buddle.

D--Board. E--Transverse buddle. F--Shovel. G--Scrubber.]

A simple buddle is made in the following way. In the first place, the

head is higher than the rest of the buddle, and is three feet long and a

foot and a half broad; this head is made of planks laid upon a timber

and fastened, and on both sides, side-boards are set up so as to hold

the water, which flows in through a pipe or trough, so that it shall

fall straight down. The middle of the head is somewhat depressed in

order that the broken rock and the larger metallic particles may settle

into it. The buddle is sunk into the earth to a depth of three-quarters

of a foot below the head, and is twelve feet long and a foot and a half

wide and deep; the bottom and each side are lined with planks to prevent

the earth, when it is softened by the water, from falling in or from

absorbing the metallic particles. The lower end of the buddle is

obstructed by a board, which is not as high as the sides. To this

straight buddle there is joined a second transverse buddle, six feet

long and a foot and a half wide and deep, similarly lined with planks;

at the lower end it is closed up with a board, also lower than the

sides of the buddle so that the water can flow away; this water falls

into a launder and is carried outside the building. In this simple

buddle is washed the metallic material which has passed on to the floor

of the works through the five large sieves. When this has been gathered

into a heap, the washer throws it into the head of the buddle, and water

is poured upon it through the pipe or small trough, and the portion

which sinks and settles in the middle of the head compartment he stirs

with a wooden scrubber,--this is what we will henceforth call the

implement made of a stick to which is fixed a piece of wood a foot long

and a palm broad. The water is made turbid by this stirring, and carries

the mud and sand and small particles of metal into the buddle below.

Together with the broken rock, the larger metallic particles remain in

the head compartment, and when these have been removed, boys throw them

upon the platform of a washing tank or the short strake, and separate

them from the broken rock. When the buddle is full of mud and sand, the

washer closes the pipe through which the water flows into the head; very

soon the water which remains in the buddle flows away, and when this has

taken place, he removes with a shovel the mud and sand which are mixed

with minute particles of metal, and washes them on a canvas strake.

Sometimes before the buddles have been filled full, the boys throw the

material into a bowl and carry it to the strakes and wash it.

Pulverized ore is washed in the head of this kind of a buddle; but

usually when tin-stone is washed in it, interlacing fir boughs are put

into the buddle, in the same manner as in the sluice when wet ore is

crushed with stamps. The larger tin-stone particles, which sink in the

upper part of the buddle, are washed separately in a strake; those

particles which are of medium size, and settle in the middle part, are

washed separately in the same way; and the mud mixed with minute

particles of tin-stone, which has settled in the lowest part of the

buddle below the fir boughs, is washed separately on the canvas strakes.

[Illustration 302 (Buddles): A--Pipe. B--Cross launder. C--Small

troughs. D--Head of the buddle. E--Wooden scrubber. F--Dividing boards.

G--Short strake.]

The divided buddle differs from the last one by having several

cross-boards, which, being placed inside it, divide it off like steps;

if the buddle is twelve feet long, four of them are placed within; if

nine feet long, three. The nearer each one is to the head, the greater

is its height; the further from the head, the lower it is; and so when

the highest is a foot and a palm high, the second is usually a foot and

three digits high, the third a foot and two digits, and the lowest a

foot and one digit. In this buddle is generally washed that

metalliferous material which has been sifted through the large sieve

into the tub containing water. This material is continuously thrown with

an iron shovel into the head of the buddle, and the water which has been

let in is stirred up by a wooden scrubber, until the buddle is full,

then the cross-boards are taken out by the washer, and the water is

drained off; next the metalliferous material which has settled in the

compartments is again washed, either on a short strake or on the canvas

strakes or in the jigging sieves. Since a short strake is often united

with the upper part of this buddle, a pipe in the first place carries

the water into a cross launder, from which it flows down through one

little launder into the buddle, and through another into the short

strake.

[Illustration 303 (Washing material): A--Head. B--Strake. C--Trowel.

D--Scrubber. E--Canvas. F--Rod by which the canvas is made smooth.]

An ordinary strake, so far as the planks are concerned, is not unlike

the last two. The head of this, as of the others, is first made of earth

stamped down, then covered with planks; and where it is necessary, earth

is thrown in and beaten down a second time, so that no crevice may

remain through which water carrying the particles of metal can escape.

The water ought to fall straight down into the strake, which has a

length of eight feet and a breadth of a foot and a half; it is

connected with a transverse launder, which then extends to a settling

pit outside the building. A boy with a shovel or a ladle takes the

impure concentrates or impure tin-stone from a heap, and throws them

into the head of the strake or spreads them over it. A washer with a

wooden scrubber then agitates them in the strake, whereby the mud mixed

with water flows away into the transverse launder, and the concentrates

or the tin-stone settle on the strake. Since sometimes the concentrates

or fine tin-stone flow down together with the mud into the transverse

launder, a second washer closes it, after a distance of about six feet,

with a cross-board and frequently stirs the mud with a shovel, in order

that when mixed with water it may flow out into the settling-pit; and

there remains in the launder only the concentrates or tin-stone. The

tin-stuff of Schlackenwald and Erbisdorff is washed in this kind of a

strake once or twice; those of Altenberg three or four times; those of

Geyer often seven times; for in the ore at Schlackenwald and Erbisdorff

the tin-stone particles are of a fair size, and are crushed with stamps;

at Altenberg they are of much smaller size, and in the broken ore at

Geyer only a few particles of tin-stone can be seen occasionally.

This method of washing was first devised by the miners who treated tin

ore, whence it passed on from the works of the tin workers to those of

the silver workers and others; this system is even more reliable than

washing in jigging-sieves. Near this ordinary strake there is generally

a canvas strake.

[Illustration 305 (Washing material): A--Upper cross launder. B--Small

launders. C--Heads of strakes. D--Strakes. E--Lower transverse launder.

F--Settling pit. G--Socket in the sill. H--Halved iron rings fixed to

beam. I--Pole. K--Its little scrubber. L--Second small scrubber.]

In modern times two ordinary strakes, similarly made, are generally

joined together; the head of one is three feet distant from that of the

other, while the bodies are four feet distant from each other, and there

is only one cross launder under the two strakes. One boy shovels, from

the heap into the head of each, the concentrates or tin-stone mixed with

mud. There are two washers, one of whom sits at the right side of one

strake, and the other at the left of the other strake, and each pursues

his task, using the following sort of implement. Under each strake is a

sill, from a socket in which a round pole rises, and is held by half an

iron ring in a beam of the building, so that it may revolve; this pole

is nine feet long and a palm thick. Penetrating the pole is a small

round piece of wood, three palms long and as many digits thick, to which

is affixed a small board two feet long and five digits wide, in an

opening of which one end of a small axle revolves, and to this axle is

fixed the handle of a little scrubber. The other end of this axle turns

in an opening of a second board, which is likewise fixed to a small

round piece of wood; this round piece, like the first one, is three

palms long and as many digits thick, and is used by the washer as a

handle. The little scrubber is made of a stick three feet long, to the

end of which is fixed a small tablet of wood a foot long, six digits

broad, and a digit and a half thick. The washer constantly moves the

handle of this implement with one hand; in this way the little scrubber

stirs the concentrates or the fine tin-stone mixed with mud in the head

of the strake, and the mud, on being stirred, flows on to the strake. In

the other hand he holds a second little scrubber, which has a handle

of half the length, and with this he ceaselessly stirs the concentrates

or tin-stone which have settled in the upper part of the strake; in this

way the mud and water flow down into the transverse launder, and from it

into the settling-pit which is outside the building.

[Illustration 306 (Washing material): A--Trough. B--Platform. C--Wooden

scrubber.]

Before the short strake and the jigging-sieve had been invented,

metalliferous ores, especially tin, were crushed dry with stamps and

washed in a large trough hollowed out of one or two tree trunks; and at

the head of this trough was a platform, on which the ore was thrown

after being completely crushed. The washer pulled it down into the

trough with a wooden scrubber which had a long handle, and when the

water had been let into the trough, he stirred the ore with the same

scrubber.

[Illustration 307 (Washing material): A--Short strake. B--Small launder.

C--Transverse launder. D--Wooden scrubber.]

The short strake is narrow in the upper part where the water flows down

into it through the little launder; in fact it is only two feet wide; at

the lower end it is wider, being three feet and as many palms. At the

sides, which are six feet long, are fixed boards two palms high. In

other respects the head resembles the head of the simple buddle, except

that it is not depressed in the middle. Beneath is a cross launder

closed by a low board. In this short strake not only is ore agitated and

washed with a wooden scrubber, but boys also separate the concentrates

from the broken rock in them and collect them in tubs. The short strake

is now rarely employed by miners, owing to the carelessness of the boys,

which has been frequently detected; for this reason, the jigging-sieve

has taken its place. The mud which settles in the launder, if the ore is

rich, is taken up and washed in a jigging-sieve or on a canvas strake.

[Illustration 308 (Washing material): A--Beams. B--Canvas. C--Head of

strake. D--Small launder. E--Settling pit or tank. F--Wooden scrubber.

G--Tubs.]

A canvas strake is made in the following way. Two beams, eighteen feet

long and half a foot broad and three palms thick, are placed on a slope;

one half of each of these beams is partially cut away lengthwise, to

allow the ends of planks to be fastened in them, for the bottom is

covered by planks three feet long, set crosswise and laid close

together. One half of each supporting beam is left intact and rises a

palm above the planks, in order that the water that is running down may

not escape at the sides, but shall flow straight down. The head of the

strake is higher than the rest of the body, and slopes so as to enable

the water to flow away. The whole strake is covered by six stretched

pieces of canvas, smoothed with a stick. The first of them occupies the

lowest division, and the second is so laid as to slightly overlap it; on

the second division, the third is similarly laid, and so on, one on the

other. If they are laid in the opposite way, the water flowing down

carries the concentrates or particles of tin-stone under the canvas, and

a useless task is attempted. Boys or men throw the concentrates or

tin-stuff mixed with mud into the head of the strake, after the canvas

has been thus stretched, and having opened the small launder they let

the water flow in; then they stir the concentrates or tin-stone with a

wooden scrubber till the water carries them all on to the canvas; next

they gently sweep the linen with the wooden scrubber until the mud flows

into the settling-pit or into the transverse launder. As soon as there

is little or no mud on the canvas, but only concentrates or tin-stone,

they carry the canvas away and wash it in a tub placed close by. The

tin-stone settles in the tub, and the men return immediately to the same

task. Finally, they pour the water out of the tub, and collect the

concentrates or tin-stone. However, if either concentrates or tin-stone

have washed down from the canvas and settled in the settling-pit or in

the transverse launder, they wash the mud again.

[Illustration 309 (Collecting concentrates): A--Canvas strake. B--Man

dashing water on the canvas. C--Bucket. D--Bucket of another kind.

E--Man removing concentrates or tin-stone from the trough.]

Some neither remove the canvas nor wash it in the tubs, but place over

it on each edge narrow strips, of no great thickness, and fix them to

the beams with nails. They agitate the metalliferous material with

wooden scrubbers and wash it in a similar way. As soon as little or no

mud remains on the canvas, but only concentrates or fine tin-stone, they

lift one beam so that the whole strake rests on the other, and dash it

with water, which has been drawn with buckets out of the small tank, and

in this way all the sediment which clings to the canvas falls into the

trough placed underneath. This trough is hewn out of a tree and placed

in a ditch dug in the ground; the interior of the trough is a foot wide

at the top, but narrower in the bottom, because it is rounded out. In

the middle of this trough they put a cross-board, in order that the

fairly large particles of concentrates or fairly large-sized tin-stone

may remain in the forepart into which they have fallen, and the fine

concentrates or fine tin-stone in the lower part, for the water flows

from one into the other, and at last flows down through an opening into

the pit. As for the fairly large-sized concentrates or tin-stone which

have been removed from the trough, they are washed again on the ordinary

strake. The fine concentrates and fine tin-stone are washed again on

this canvas strake. By this method, the canvas lasts longer because it

remains fixed, and nearly double the work is done by one washer as

quickly as can be done by two washers by the other method.

[Illustration 311 (Jigging Sieve): A--Fine sieves. B--Limp. C--Finer

sieve. D--Finest sieve.]

The jigging sieve has recently come into use by miners. The

metalliferous material is thrown into it and sifted in a tub nearly full

of water. The sieve is shaken up and down, and by this movement all the

material below the size of a pea passes through into the tub, and the

rest remains on the bottom of the sieve. This residue is of two kinds,

the metallic particles, which occupy the lower place, and the particles

of rock and earth, which take the higher place, because the heavy

substance always settles, and the light is borne upward by the force of

the water. This light material is taken away with a limp, which is a

thin tablet of wood almost semicircular in shape, three-quarters of a

foot long, and half a foot wide. Before the lighter portion is taken

away the contents of the sieve are generally divided crosswise with a

limp, to enable the water to penetrate into it more quickly. Afterward

fresh material is again thrown into the sieve and shaken up and down,

and when a great quantity of metallic particles have settled in the

sieve, they are taken out and put into a tray close by. But since there

fall into the tub with the mud, not only particles of gold or silver,

but also of sand, pyrites, _cadmia_, galena, quartz, and other

substances, and since the water cannot separate these from the metallic

particles because they are all heavy, this muddy mixture is washed a

second time, and the part which is useless is thrown away. To prevent

the sieve passing this sand again too quickly, the washer lays small

stones or gravel in the bottom of the sieve. However, if the sieve is

not shaken straight up and down, but is tilted to one side, the small

stones or broken ore move from one part to another, and the metallic

material again falls into the tub, and the operation is frustrated. The

miners of our country have made an even finer sieve, which does not fail

even with unskilled washers; in washing with this sieve they have no

need for the bottom to be strewn with small stones. By this method the

mud settles in the tub with the very fine metallic particles, and the

larger sizes of metal remain in the sieve and are covered with the

valueless sand, and this is taken away with a limp. The concentrates

which have been collected are smelted together with other things. The

mud mixed with the very fine metallic particles is washed for a third

time and in the finest sieve, whose bottom is woven of hair. If the ore

is rich in metal, all the material which has been removed by the limp is

washed on the canvas strakes, or if the ore is poor it is thrown away.

I have explained the methods of washing which are used in common for the

ores of many metals. I now come to another method of crushing ore, for I

ought to speak of this before describing those methods of washing which

are peculiar to ores of particular metals.

[Illustration 313 (Stamp-mill): A--Mortar. B--Open end of mortar.

C--Slab of rock. D--Iron sole plates. E--Screen. F--Launder. G--Wooden

shovel. H--Settling pit. I--Iron shovel. K--Heap of material which has

settled. L--Ore which requires crushing. M--Small launder.]

In the year 1512, George, the illustrious Duke of Saxony[14], gave the

overlordship of all the dumps ejected from the mines in Meissen to the

noble and wise Sigismund Maltitz, father of John, Bishop of Meissen.

Rejecting the dry stamps, the large sieve, and the stone mills of

Dippoldswalde and Altenberg, in which places are dug the small black

stones from which tin is smelted, he invented a machine which could

crush the ore wet under iron-shod stamps. That is called "wet ore" which

is softened by water which flows into the mortar box, and they are

sometimes called "wet stamps" because they are drenched by the same

water; and on the other hand, the other kinds are called "dry stamps" or

"dry ore," because no water is used to soften the ore when the stamps

are crushing. But to return to our subject. This machine is not

dissimilar to the one which crushes the ore with dry iron-shod stamps,

but the heads of the wet stamps are larger by half than the heads of the

others. The mortar-box, which is made of oak or beech timber, is set up

in the space between the upright posts; it does not open in front, but

at one end, and it is three feet long, three-quarters of a foot wide,

and one foot and six digits deep. If it has no bottom, it is set up in

the same way over a slab of hard, smooth rock placed in the ground,

which has been dug down a little. The joints are stopped up all round

with moss or cloth rags. If the mortar has a bottom, then an iron

sole-plate, three feet long, three-quarters of a foot wide, and a palm

thick, is placed in it. In the opening in the end of the mortar there is

fixed an iron plate full of holes, in such a way that there is a space

of two digits between it and the shoe of the nearest stamp, and the same

distance between this screen and the upright post, in an opening through

which runs a small but fairly long launder. The crushed particles of

silver ore flow through this launder with the water into a settling-pit,

while the material which settles in the launder is removed with an iron

shovel to the nearest planked floor; that material which has settled in

the pit is removed with an iron shovel on to another floor. Most people

make two launders, in order that while the workman empties one of them

of the accumulation which has settled in it, a fresh deposit may be

settling in the other. The water flows in through a small launder at the

other end of the mortar that is near the water-wheel which turns the

machine. The workman throws the ore to be crushed into the mortar in

such a way that the pieces, when they are thrown in among the stamps, do

not impede the work. By this method a silver or gold ore is crushed very

fine by the stamps.

[Illustration 314 (Buddle): A--Launder reaching to the screen.

B--Transverse trough. C--Spouts. D--Large buddles. E--Shovel.

F--Interwoven twigs. G--Boards closing the buddles. H--Cross trough.]

When tin ore is crushed by this kind of iron-shod stamps, as soon as

crushing begins, the launder which extends from the screen discharges

the water carrying the fine tin-stone and fine sand into a transverse

trough, from which the water flows down through the spouts, which pierce

the side of the trough, into the one or other of the large buddles set

underneath. The reason why there are two is that, while the washer

empties the one which is filled with fine tin-stone and sand, the

material may flow into the other. Each buddle is twelve feet long, one

cubit deep, and a foot and a half broad. The tin-stone which settles in

the upper part of the buddles is called the large size; these are

frequently stirred with a shovel, in order that the medium sized

particles of tin-stone, and the mud mixed with the very fine particles

of the stones may flow away. The particles of medium size generally

settle in the middle part of the buddle, where they are arrested by

interwoven fir twigs. The mud which flows down with the water settles

between the twigs and the board which closes the lower end of the

buddle. The tin-stone of large size is removed separately from the

buddle with a shovel; those of medium size are also removed separately,

and likewise the mud is removed separately, for they are separately

washed on the canvas strakes and on the ordinary strake, and separately

roasted and smelted. The tin-stone which has settled in the middle part

of the buddle, is also always washed separately on the canvas strakes;

but if the particles are nearly equal in size to those which have

settled in the upper part of the buddle, they are washed with them in

the ordinary strake and are roasted and smelted with them. However, the

mud is never washed with the others, either on the canvas strakes or on

the ordinary strake, but separately, and the fine tin-stone which is

obtained from it is roasted and smelted separately. The two large

buddles discharge into a cross trough, and it again empties through a

launder into a settling-pit which is outside the building.

This method of washing has lately undergone a considerable change; for

the launder which carries the water, mixed with the crushed tin-stone

and fine sand which flow from the openings of the screen, does not reach

to a transverse trough which is inside the same room, but runs straight

through a partition into a small settling-pit. A boy draws a

three-toothed rake through the material which has settled in the portion

of the launder outside the room, by which means the larger sized

particles of tin-stone settle at the bottom, and these the washer takes

out with the wooden shovel and carries into the room; this material is

thrown into an ordinary strake and swept with a wooden scrubber and

washed. As for those tin-stone particles which the water carries off

from the strake, after they have been brought back on to the strake, he

washes them again until they are clean.

[Illustration 315 (Buddle): A--First launder. B--Three-toothed rake.

C--Small settling pit. D--Large buddle. E--Buddle resembling the simple

buddle. F--Small roller. G--Boards. H--Their holes. I--Shovel.

K--Building. L--Stove. (This picture does not entirely agree with the

text).]

The remaining tin-stone, mixed with sand, flows into the small

settling-pit which is within the building, and this discharges into two

large buddles. The tin-stone of moderate size, mixed with those of

fairly large size, settle in the upper part, and the small size in the

lower part; but both are impure, and for this reason they are taken out

separately and the former is washed twice, first in a buddle like the

simple buddle, and afterward on an ordinary strake. Likewise the latter

is washed twice, first on a canvas strake and afterward on an ordinary

strake. This buddle, which is like the simple buddle, differs from it in

the head, the whole of which in this case is sloping, while in the case

of the other it is depressed in the centre. In order that the boy may be

able to rest the shovel with which he cleanses the tin-stone, this

sluice has a small wooden roller which turns in holes in two thick

boards fixed to the sides of the buddle; if he did not do this, he would

become over-exhausted by his task, for he spends whole days standing

over these labours. The large buddle, the one like the simple buddle,

the ordinary strake, and the canvas strakes, are erected within a

special building. In this building there is a stove that gives out heat

through the earthen tiles or iron plates of which it is composed, in

order that the washers can pursue their labours even in winter, if the

rivers are not completely frozen over.

[Illustration 317 (Workroom with settling-pit): A--Launder from the

screen of the mortar-box. B--Three-toothed rake. C--Small settling-pit.

D--Canvas. E--Strakes. F--Brooms.]

On the canvas strakes are washed the very fine tin-stone mixed with mud

which has settled in the lower end of the large buddle, as well as in

the lower end of the simple buddle and of the ordinary strake. The

canvas is cleaned in a trough hewn out of one tree trunk and partitioned

off with two boards, so that three compartments are made. The first and

second pieces of canvas are washed in the first compartment, the third

and fourth in the second compartment, the fifth and sixth in the third

compartment. Since among the very fine tin-stone there are usually some

grains of stone, rock, or marble, the master cleanses them on the

ordinary strake, lightly brushing the top of the material with a broom,

the twigs of which do not all run the same way, but some straight and

some crosswise. In this way the water carries off these impurities from

the strake into the settling-pit because they are lighter, and leaves

the tin-stone on the table because it is heavier.

Below all buddles or strakes, both inside and outside the building,

there are placed either settling-pits or cross-troughs into which they

discharge, in order that the water may carry on down into the stream but

very few of the most minute particles of tin-stone. The large

settling-pit which is outside the building is generally made of joined

flooring, and is eight feet in length, breadth and depth. When a large

quantity of mud, mixed with very fine tin-stone, has settled in it,

first of all the water is let out by withdrawing a plug, then the mud

which is taken out is washed outside the house on the canvas strakes,

and afterward the concentrates are washed on the strake which is inside

the building. By these methods the very finest tin-stone is made clean.

[Illustration 318 (Streaming for Tin): A--River. B--Weir. C--Gate.

D--Area. E--Meadow. F--Fence. G--Ditch.]

The mud mixed with the very fine tin-stone, which has neither settled in

the large settling-pit nor in the transverse launder which is outside

the room and below the canvas strakes, flows away and settles in the bed

of the stream or river. In order to recover even a portion of the fine

tin-stone, many miners erect weirs in the bed of the stream or river,

very much like those that are made above the mills, to deflect the

current into the races through which it flows to the water-wheels. At

one side of each weir there is an area dug out to a depth of five or six

or seven feet, and if the nature of the place will permit, extending

in every direction more than sixty feet. Thus, when the water of the

river or stream in autumn and winter inundates the land, the gates of

the weir are closed, by which means the current carries the mud mixed

with fine tin-stone into the area. In spring and summer this mud is

washed on the canvas strakes or on the ordinary strake, and even the

finest black-tin is collected. Within a distance of four thousand

fathoms along the bed of the stream or river below the buildings in

which the tin-stuff is washed, the miners do not make such weirs, but

put inclined fences in the meadows, and in front of each fence they dig

a ditch of the same length, so that the mud mixed with the fine

tin-stone, carried along by the stream or river when in flood, may

settle in the ditch and cling to the fence. When this mud is collected,

it is likewise washed on canvas strakes and on the ordinary strake, in

order that the fine tin-stone may be separated from it. Indeed we may

see many such areas and fences collecting mud of this kind in Meissen

below Altenberg in the river Moglitz,--which is always of a reddish

colour when the rock containing the black tin is being crushed under the

stamps.

[Illustration 320 (Stamp-mill): A--First machine. B--Its stamps. C--Its

mortar-box. D--Second machine. E--Its stamps. F--Its mortar-box.

G--Third machine. H--Its stamps. I--Its mortar-box. K--Fourth machine.

L--Its stamps. M--Its mortar-box.]

But to return to the stamping machines. Some usually set up four

machines of this kind in one place, that is to say, two above and the

same number below. By this plan it is necessary that the current which

has been diverted should fall down from a greater height upon the upper

water-wheels, because these turn axles whose cams raise heavier stamps.

The stamp-stems of the upper machines should be nearly twice as long as

the stems of the lower ones, because all the mortar-boxes are placed on

the same level. These stamps have their tappets near their upper ends,

not as in the case of the lower stamps, which are placed just above the

bottom. The water flowing down from the two upper water-wheels is caught

in two broad races, from which it falls on to the two lower

water-wheels. Since all these machines have the stamps very close

together, the stems should be somewhat cut away, to prevent the iron

shoes from rubbing each other at the point where they are set into the

stems. Where so many machines cannot be constructed, by reason of the

narrowness of the valley, the mountain is excavated and levelled in two

places, one of which is higher than the other, and in this case two

machines are constructed and generally placed in one building. A broad

race receives in the same way the water which flows down from the upper

water-wheel, and similarly lets it fall on the lower water-wheel. The

mortar-boxes are not then placed on one level, but each on the level

which is appropriate to its own machine, and for this reason, two

workmen are then required to throw ore into the mortar-boxes. When no

stream can be diverted which will fall from a higher place upon the top

of the water-wheel, one is diverted which will turn the foot of the

wheel; a great quantity of water from the stream is collected in one

pool capable of holding it, and from this place, when the gates are

raised, the water is discharged against the wheel which turns in the

race. The buckets of a water-wheel of this kind are deeper and bent

back, projecting upward; those of the former are shallower and bent

forward, inclining downward.

[Illustration 321 (Stamp-mill): A--Stamps. B--Mortar. C--Plates full of

holes. D--Transverse launder. E--Planks full of cup-like depressions.

F--Spout. G--Bowl into which the concentrates fall. H--Canvas strake.

I--Bowls shaped like a small boat. K--Settling-pit under the canvas

strake.]

Further, in the Julian and Rhaetian Alps[15] and in the Carpathian

Mountains, gold or even silver ore is now put under stamps, which are

sometimes placed more than twenty in a row, and crushed wet in a long

mortar-box. The mortar has two plates full of holes through which the

ore, after being crushed, flows out with the water into the transverse

launder placed underneath, and from there it is carried down by two

spouts into the heads of the canvas strakes. Each head is made of a

thick broad plank, which can be raised and set upright, and to which on

each side are fixed pieces projecting upward. In this plank there are

many cup-like depressions equal in size and similar in shape, in each of

which an egg could be placed. Right down in these depressions are small

crevices which can retain the concentrates of gold or silver, and when

the hollows are nearly filled with these materials, the plank is raised

on one side so that the concentrates will fall into a large bowl. The

cup-like depressions are washed out by dashing them with water. These

concentrates are washed separately in different bowls from those which

have settled on the canvas. This bowl is smooth and two digits wide and

deep, being in shape very similar to a small boat; it is broad in the

fore part, narrow in the back, and in the middle of it there is a cross

groove, in which the particles of pure gold or silver settle, while the

grains of sand, since they are lighter, flow out of it.

In some parts of Moravia, gold ore, which consists of quartz mixed with

gold, is placed under the stamps and crushed wet. When crushed fine it

flows out through a launder into a trough, is there stirred by a wooden

scrubber, and the minute particles of gold which settle in the upper end

of the trough are washed in a black bowl.

So far I have spoken of machines which crush wet ore with iron-shod

stamps. I will now explain the methods of washing which are in a measure

peculiar to the ore of certain metals, beginning with gold. The ore

which contains particles of this metal, and the sand of streams and

rivers which contains grains of it, are washed in frames or bowls; the

sands especially are also washed in troughs. More than one method is

employed for washing on frames, for these frames either pass or retain

the particles or concentrates of gold; they pass them if they have

holes, and retain them if they have no holes. But either the frame

itself has holes, or a box is substituted for it; if the frame itself is

perforated it passes the particles or concentrates of gold into a

trough; if the box has them, it passes the gold material into the long

sluice. I will first speak of these two methods of washing. The frame is

made of two planks joined together, and is twelve feet long and three

feet wide, and is full of holes large enough for a pea to pass. To

prevent the ore or sand with which the gold is mixed from falling out at

the sides, small projecting edge-boards are fixed to it. This frame is

set upon two stools, the first of which is higher than the second, in

order that the gravel and small stones can roll down it. The washer

throws the ore or sand into the head of the frame, which is higher, and

opening the small launder, lets the water into it, and then agitates it

with a wooden scrubber. In this way, the gravel and small stones roll

down the frame on to the ground, while the particles or concentrates of

gold, together with the sand, pass through the holes into the trough

which is placed under the frame, and after being collected are washed in

the bowl.

[Illustration 322 (Frames for Washing Ore or Alluvial): A--Head of

frame. B--Frame. C--Holes. D--Edge-boards. E--Stools. F--Scrubber.

G--Trough. H--Launder. I--Bowl.]

[Illustration 323 (Frames for Washing Ore or Alluvial): A--Sluice.

B--Box. C--Bottom of inverted box. D--Open part of it. E--Iron hoe.

F--Riffles. G--Small launder. H--Bowl with which settlings are taken

away. I--Black bowl in which they are washed.]

A box which has a bottom made of a plate full of holes, is placed over

the upper end of a sluice, which is fairly long but of moderate width.

The gold material to be washed is thrown into this box, and a great

quantity of water is let in. The lumps, if ore is being washed, are

mashed with an iron shovel. The fine portions fall through the bottom of

the box into the sluice, but the coarse pieces remain in the box, and

these are removed with a scraper through an opening which is nearly in

the middle of one side. Since a large amount of water is necessarily let

into the box, in order to prevent it from sweeping away any particles of

gold which have fallen into the sluice, the sluice is divided off by

ten, or if it is as long again, by fifteen riffles. These riffles are

placed equidistant from one another, and each is higher than the one

next toward the lower end of the sluice. The little compartments which

are thus made are filled with the material and the water which flows

through the box; as soon as these compartments are full and the water

has begun to flow over clear, the little launder through which this

water enters into the box is closed, and the water is turned in another

direction. Then the lowest riffle is removed from the sluice, and the

sediment which has accumulated flows out with the water and is caught in

a bowl. The riffles are removed one by one and the sediment from each is

taken into a separate bowl, and each is separately washed and cleansed

in a bowl. The larger particles of gold concentrates settle in the

higher compartments, the smaller size, in the lower compartments. This

bowl is shallow and smooth, and smeared with oil or some other slippery

substance, so that the tiny particles of gold may not cling to it, and

it is painted black, that the gold may be more easily discernible; on

the exterior, on both sides and in the middle, it is slightly hollowed

out in order that it may be grasped and held firmly in the hands when

shaken. By this method the particles or concentrates of gold settle in

the back part of the bowl; for if the back part of the bowl is tapped or

shaken with one hand, as is usual, the contents move toward the fore

part. In this way the Moravians, especially, wash gold ore.

The gold particles are also caught on frames which are either bare or

covered. If bare, the particles are caught in pockets; if covered, they

cling to the coverings. Pockets are made in various ways, either with

iron wire or small cross-boards fixed to the frame, or by holes which

are sunk into the sluice itself or into its head, but which do not quite

go through. These holes are round or square, or are grooves running

crosswise. The frames are either covered with skins, pieces of cloth, or

turf, which I will deal with one by one in turn.

[Illustration 324 (Frames for Washing Ore or Alluvial): A--Plank.

B--Side-boards. C--Iron wire. D--Handles.]

In order to prevent the sand which contains the particles of gold from

spilling out, the washer fixes side-boards to the edges of a plank which

is six feet long and one and a quarter wide. He then lays crosswise many

iron wires a digit apart, and where they join he fixes them to the

bottom plank with iron nails. Then he makes the head of the frame

higher, and into this he throws the sand which needs washing, and taking

in his hands the handles which are at the head of the frame, he draws it

backward and forward several times in the river or stream. In this way

the small stones and gravel flow down along the frame, and the sand

mixed with particles of gold remains in the pockets between the strips.

When the contents of the pockets have been shaken out and collected in

one place, he washes them in a bowl and thus cleans the gold dust.

[Illustration 326 (Frames for Washing Ore or Alluvial): A--Head of the

sluice. B--Riffles. C--Wooden scrubber. D--Pointed stick. E--Dish.

F--Its cup-like depression. G--Grooved dish.]

Other people, among whom are the Lusitanians[16], fix to the sides of a

sluice, which is about six feet long and a foot and a half broad, many

cross-strips or riffles, which project backward and are a digit apart.

The washer or his wife lets the water into the head of the sluice, where

he throws the sand which contains the particles of gold. As it flows

down he agitates it with a wooden scrubber, which he moves transversely

to the riffles. He constantly removes with a pointed wooden stick the

sediment which settles in the pockets between the riffles, and in this

way the particles of gold settle in them, while the sand and other

valueless materials are carried by the water into a tub placed below the

sluice. He removes the particles of metal with a small wooden shovel

into a wooden bowl. This bowl does not exceed a foot and a quarter in

breadth, and by moving it up and down in the stream he cleanses the gold

dust, for the remaining sand flows out of the dish, and the gold dust

settles in the middle of it, where there is a cup-like depression. Some

make use of a bowl which is grooved inside like a shell, but with a

smooth lip where the water flows out. This smooth place, however, is

narrower where the grooves run into it, and broader where the water

flows out.

[Illustration 327 (Frames for Washing Ore or Alluvial): A--Head of the

sluice. B--Side-boards. C--Lower end of the sluice. D--Pockets.

E--Grooves. F--Stools. G--Shovel. H--Tub set below. I--Launder.]

The cup-like pockets and grooves are cut or burned at the same time into

the bottom of the sluice; the bottom is composed of three planks ten

feet long, and is about four feet wide; but the lower end, through which

the water is discharged, is narrower. This sluice, which likewise has

side-boards fixed to its edges, is full of rounded pockets and of

grooves which lead to them, there being two grooves to one pocket, in

order that the water mixed with sand may flow into each pocket through

the upper groove, and that after the sand has partly settled, the water

may again flow out through the lower groove. The sluice is set in the

river or stream or on the bank, and placed on two stools, of which the

first is higher than the second in order that the gravel and small

stones may roll down the sluice. The washer throws sand into the head

with a shovel, and opening the launder, lets in the water, which carries

the particles of metal with a little sand down into the pockets, while

the gravel and small stones with the rest of the sand falls into a tub

placed below the sluice. As soon as the pockets are filled, he brushes

out the concentrates and washes them in a bowl. He washes again and

again through this sluice.

[Illustration 328 (Frames for Washing Ore or Alluvial): A--Cross

grooves. B--Tub set under the sluice. C--Another tub.]

Some people cut a number of cross-grooves, one palm distant from each

other, in a sluice similarly composed of three planks eight feet long.

The upper edge of these grooves is sloping, that the particles of gold

may slip into them when the washer stirs the sand with a wooden shovel;

but their lower edge is vertical so that the gold particles may thus be

unable to slide out of them. As soon as these grooves are full of gold

particles mixed with fine sand, the sluice is removed from the stools

and raised up on its head. The head in this case is nothing but the

upper end of the planks of which the sluice is composed. In this way the

metallic particles, being turned over backward, fall into another tub,

for the small stones and gravel have rolled down the sluice. Some people

place large bowls under the sluice instead of tubs, and as in the other

cases, the unclean concentrates are washed in the small bowl.

[Illustration 329 (Frames for Washing Ore or Alluvial): A--Sluice

covered with canvas. B--Its head full of pockets and grooves. C--Head

removed and washed in a tub. D--Sluice which has square pockets.

E--Sluice to whose planks small shavings cling. F--Broom. G--Skins of

oxen. H--Wooden scrubber.]

The Thuringians cut rounded pockets, a digit in diameter and depth, in

the head of the sluice, and at the same time they cut grooves reaching

from one to another. The sluice itself they cover with canvas. The sand

which is to be washed, is thrown into the head and stirred with a

wooden scrubber; in this way the water carries the light particles of

gold on to the canvas, and the heavy ones sink in the pockets, and when

these hollows are full, the head is removed and turned over a tub, and

the concentrates are collected and washed in a bowl. Some people make

use of a sluice which has square pockets with short vertical recesses

which hold the particles of gold. Other workers use a sluice made of

planks, which are rough by reason of the very small shavings which still

cling to them; these sluices are used instead of those with coverings,

of which this sluice is bare, and when the sand is washed, the particles

of gold cling no less to these shavings than to canvas, or skins, or

cloths, or turf. The washer sweeps the sluice upward with a broom, and

when he has washed as much of the sand as he wishes, he lets a more

abundant supply of water into the sluice again to wash out the

concentrates, which he collects in a tub set below the sluice, and then

washes again in a bowl. Just as Thuringians cover the sluice with

canvas, so some people cover it with the skins of oxen or horses. They

push the auriferous sand upward with a wooden scrubber, and by this

system the light material flows away with the water, while the particles

of gold settle among the hairs; the skins are afterward washed in a tub;

and the concentrates are collected in a bowl.

[Illustration 330 (Washing material in spring): A--Spring. B--Skin.

C--Argonauts.]

The Colchians[17] placed the skins of animals in the pools of springs;

and since many particles of gold had clung to them when they were

removed, poets invented the "golden fleece" of the Colchians. In like

manner, it can be contrived by the methods of miners that skins should

take up, not only particles of gold, but also of silver and gems.

[Illustration 331 (Frames for Washing Ore or Alluvial): A--Head of

frame. B--Frame. C--Cloth. D--small launder. E--Tub set below the frame.

F--Tub in which cloth is washed.]

Many people cover the frame with a green cloth as long and wide as the

frame itself, and fasten it with iron nails in such a way that they can

easily draw them out and remove the cloth. When the cloth appears to be

golden because of the particles which adhere to it, it is washed in a

special tub and the particles are collected in a bowl. The remainder

which has run down into the tub is again washed on the frame.

[Illustration 332 (Frames for Washing Ore or Alluvial): A--Cloth full

of small knots, spread out. B--Small knots more conspicuously shown.

C--Tub in which cloth is washed.]

Some people, in place of a green cloth, use a cloth of tightly woven

horsehair, which has a rough knotty surface. Since these knots stand out

and the cloth is rough, even the very small particles of gold adhere to

it; these cloths are likewise washed in a tub with water.

[Illustration 333 (Frames for Washing Ore or Alluvial): A--Head of

frame. B--Small launder through which water flows into head of frame.

C--Pieces of turf. D--Trough placed under frame. E--Tub in which pieces

of turf are washed.]

Some people construct a frame not unlike the one covered with canvas,

but shorter. In place of the canvas they set pieces of turf in rows.

They wash the sand, which has been thrown into the head of the frame, by

letting in water. In this way the particles of gold settle in the turf,

the mud and sand, together with the water, are carried down into the

settling-pit or trough below, which is opened when the work is finished.

After all the water has passed out of the settling-pit, the sand and mud

are carried away and washed over again in the same manner. The particles

which have clung to the turf are afterward washed down into the

settling-pit or trough by a stronger current of the water, which is let

into the frame through a small launder. The concentrates are finally

collected and washed in a bowl. Pliny was not ignorant of this method of

washing gold. "The ulex," he says, "after being dried, is burnt, and its

ashes are washed over a grassy turf, that the gold may settle on it."

[Illustration 334 (Trays for Washing Alluvial): A--Tray. B--Bowl-like

depression. C--Handles.]

Sand mixed with particles of gold is also washed in a tray, or in a

trough or bowl. The tray is open at the further end, is either hewn out

of a squared trunk of a tree or made out of a thick plank to which

side-boards are fixed, and is three feet long, a foot and a half wide,

and three digits deep. The bottom is hollowed out into the shape of an

elongated bowl whose narrow end is turned toward the head, and it has

two long handles, by which it is drawn backward and forward in the

river. In this way the fine sand is washed, whether it contains

particles of gold or the little black stones from which tin is made.

[Illustration 335 (Trough for washing alluvial): A--Trough. B--Its open

end. C--End that may be closed. D--Stream. E--Hoe. F--End-board.

G--Bag.]

The Italians who come to the German mountains seeking gold, in order to

wash the river sand which contains gold-dust and garnets,[19] use a

fairly long shallow trough hewn out of a tree, rounded within and

without, open at one end and closed at the other, which they turn in the

bed of the stream in such a way that the water does not dash into it,

but flows in gently. They stir the sand, which they throw into it, with

a wooden hoe, also rounded. To prevent the particles of gold or garnets

from running out with the light sand, they close the end with a board

similarly rounded, but lower than the sides of the trough. The

concentrates of gold or garnets which, with a small quantity of heavy

sand, have settled in the trough, they wash in a bowl and collect in

bags and carry away with them.

[Illustration 336 (Bowls for Alluvial Washing): A--Large bowl. B--Ropes.

C--Beam. D--Other large bowl which coiners use. E--Small bowl.]

Some people wash this kind of sand in a large bowl which can easily be

shaken, the bowl being suspended by two ropes from a beam in a building.

The sand is thrown into it, water is poured in, then the bowl is shaken,

and the muddy water is poured out and clear water is again poured in,

this being done again and again. In this way, the gold particles settle

in the back part of the bowl because they are heavy, and the sand in the

front part because it is light; the latter is thrown away, the former

kept for smelting. The one who does the washing then returns immediately

to his task. This method of washing is rarely used by miners, but

frequently by coiners and goldsmiths when they wash gold, silver, or

copper. The bowl they employ has only three handles, one of which they

grasp in their hands when they shake the bowl, and in the other two is

fastened a rope by which the bowl is hung from a beam, or from a

cross-piece which is upheld by the forks of two upright posts fixed in

the ground. Miners frequently wash ore in a small bowl to test it. This

bowl, when shaken, is held in one hand and thumped with the other hand.

In other respects this method of washing does not differ from the last.

[Illustration 337 (Ground Sluicing): A--Stream. B--Ditch. C--Mattock.

D--Pieces of turf. E--Seven-pronged fork. F--Iron shovel. G--Trough.

H--Another trough below it. I--Small wooden trowel.]

I have spoken of the various methods of washing sand which contains

grains of gold; I will now speak of the methods of washing the material

in which are mixed the small black stones from which tin is made[20].

Eight such methods are in use, and of these two have been invented

lately. Such metalliferous material is usually found torn away from

veins and stringers and scattered far and wide by the impetus of water,

although sometimes _venae dilatatae_ are composed of it. The miners dig

out the latter material with a broad mattock, while they dig the former

with a pick. But they dig out the little stones, which are not rare in

this kind of ore, with an instrument like the bill of a duck. In

districts which contain this material, if there is an abundant supply of

water, and if there are valleys or gentle slopes and hollows, so that

rivers can be diverted into them, the washers in summer-time first of

all dig a long ditch sloping so that the water will run through it

rapidly. Into the ditch is thrown the metallic material, together with

the surface material, which is six feet thick, more or less, and often

contains moss, roots of plants, shrubs, trees, and earth; they are all

thrown in with a broad mattock, and the water flows through the ditch.

The sand and tin-stone, as they are heavy, sink to the bottom of the

ditch, while the moss and roots, as they are light, are carried away by

the water which flows through the ditch. The bottom of the ditch is

obstructed with turf and stones in order to prevent the water from

carrying away the tin-stone at the same time. The washers, whose feet

are covered with high boots made of hide, though not of rawhide,

themselves stand in the ditch and throw out of it the roots of the

trees, shrubs, and grass with seven-pronged wooden forks, and push back

the tin-stone toward the head of the ditch. After four weeks, in which

they have devoted much work and labour, they raise the tin-stone in the

following way; the sand with which it is mixed is repeatedly lifted from

the ditch with an iron shovel and agitated hither and thither in the

water, until the sand flows away and only the tin-stone remains on the

shovel. The tin-stone is all collected together and washed again in a

trough by pushing it up and turning it over with a wooden trowel, in

order that the remaining sand may separate from it. Afterward they

return to their task, which they continue until the metalliferous

material is exhausted, or until the water can no longer be diverted into

the ditches.

[Illustration 338 (Sluicing Tin): A--Trough. B--Wooden shovel. C--Tub.

D--Launder. E--Wooden trowel. F--Transverse trough. G--Plug. H--Falling

water. I--Ditch. K--Barrow conveying material to be washed. L--Pick like

the beak of a duck with which the miner digs out the material from which

the small stones are obtained.]

The trough which I mentioned is hewn out of the trunk of a tree and the

interior is five feet long, three-quarters of a foot deep, and six

digits wide. It is placed on an incline and under it is put a tub which

contains interwoven fir twigs, or else another trough is put under it,

the interior of which is three feet long and one foot wide and deep; the

fine tin-stone, which has run out with the water, settles in the bottom.

Some people, in place of a trough, put a square launder underneath, and

in like manner they wash the tin-stone in this by agitating it up and

down and turning it over with a small wooden trowel. A transverse trough

is put under the launder, which is either open on one end and drains off

into a tub or settling-pit, or else is closed and perforated through the

bottom; in this case, it drains into a ditch beneath, where the water

falls when the plug has been partly removed. The nature of this ditch I

will now describe.

[Illustration 340 (Sluicing Tin): A--Launder. B--Interlacing fir twigs.

C--Logs; three on one side, for the fourth cannot be seen because the

ditch is so full with material now being washed. D--Logs at the head of

the ditch. E--Barrow. F--Seven-pronged fork. G--Hoe.]

If the locality does not supply an abundance of water, the washers dig a

ditch thirty or thirty-six feet long, and cover the bottom, the full

length, with logs joined together and hewn on the side which lies flat

on the ground. On each side of the ditch, and at its head also, they

place four logs, one above the other, all hewn smooth on the inside. But

since the logs are laid obliquely along the sides, the upper end of the

ditch is made four feet wide and the tail end, two feet. The water has a

high drop from a launder and first of all it falls into interlaced fir

twigs, in order that it shall fall straight down for the most part in an

unbroken stream and thus break up the lumps by its weight. Some do not

place these twigs under the end of the launder, but put a plug in its

mouth, which, since it does not entirely close the launder, nor

altogether prevent the discharge from it, nor yet allow the water to

spout far afield, makes it drop straight down. The workman brings in a

wheelbarrow the material to be washed, and throws it into the ditch. The

washer standing in the upper end of the ditch breaks the lumps with a

seven-pronged fork, and throws out the roots of trees, shrubs, and grass

with the same instrument, and thereby the small black stones settle

down. When a large quantity of the tin-stone has accumulated, which

generally happens when the washer has spent a day at this work, to

prevent it from being washed away he places it upon the bank, and other

material having been again thrown into the upper end of the ditch, he

continues the task of washing. A boy stands at the lower end of the

ditch, and with a thin pointed hoe stirs up the sediment which has

settled at the lower end, to prevent the washed tin-stone from being

carried further, which occurs when the sediment has accumulated to such

an extent that the fir branches at the outlet of the ditch are covered.

[Illustration 341 (Sifting Ore): A--Strakes. B--Tank. C--Launder.

D--Plug. E--Wooden shovel. F--Wooden mallet. G--Wooden shovel with short

handle. H--The plug in the strake. I--Tank placed under the plug.]

The third method of washing materials of this kind follows. Two strakes

are made, each of which is twelve feet long and a foot and a half wide

and deep. A tank is set at their head, into which the water flows

through a little launder. A boy throws the ore into one strake; if it is

of poor quality he puts in a large amount of it, if it is rich he puts

in less. The water is let in by removing the plug, the ore is stirred

with a wooden shovel, and in this way the tin-stone, mixed with the

heavier material, settles in the bottom of the strake, and the water

carries the light material into the launder, through which it flows on

to a canvas strake. The very fine tin-stone, carried by the water,

settles on to the canvas and is cleansed. A low cross-board is placed in

the strake near the head, in order that the largest sized tin-stone may

settle there. As soon as the strake is filled with the material which

has been washed, he closes the mouth of the tank and continues washing

in the other strake, and then the plug is withdrawn and the water and

tin-stone flow down into a tank below. Then he pounds the sides of the

loaded strake with a wooden mallet, in order that the tin-stone clinging

to the sides may fall off; all that has settled in it, he throws out

with a wooden shovel which has a short handle. Silver slags which have

been crushed under the stamps, also fragments of silver-lead alloy and

of cakes melted from pyrites, are washed in a strake of this kind.

[Illustration 342 (Sifting Ore): A--Sieve. B--Tub. C--Water flowing out

of the bottom of it. D--Strake. E--Three-toothed rake. F--Wooden

scrubber.]

Material of this kind is also washed while wet, in a sieve whose bottom

is made of woven iron wire, and this is the fourth method of washing.

The sieve is immersed in the water which is contained in a tub, and is

violently shaken. The bottom of this tub has an opening of such size

that as much water, together with tailings from the sieve, can flow

continuously out of it as water flows into it. The material which

settles in the strake, a boy either digs over with a three-toothed iron

rake or sweeps with a wooden scrubber; in this way the water carries off

a great part of both sand and mud. The tin-stone or metalliferous

concentrates settle in the strake and are afterward washed in another

strake.

[Illustration 343 (Sluicing Tin): A--Box. B--Perforated plate.

C--Trough. D--Cross-boards. E--Pool. F--Launder. G--Shovel. H--Rake.]

These are ancient methods of washing material which contains tin-stone;

there follow two modern methods. If the tin-stone mixed with earth or

sand is found on the slopes of mountains or hills, or in the level

fields which are either devoid of streams or into which a stream cannot

be diverted, miners have lately begun to employ the following method of

washing, even in the winter months. An open box is constructed of

planks, about six feet long, three feet wide, and two feet and one palm

deep. At the upper end on the inside, an iron plate three feet long and

wide is fixed, at a depth of one foot and a half from the top; this

plate is very full of holes, through which tin-stone about the size of a

pea can fall. A trough hewn from a tree is placed under the box, and

this trough is about twenty-four feet long and three-quarters of a foot

wide and deep; very often three cross-boards are placed in it, dividing

it off into compartments, each one of which is lower than the next. The

turbid waters discharge into a settling-pit.

The metalliferous material is sometimes found not very deep beneath the

surface of the earth, but sometimes so deep that it is necessary to

drive tunnels and sink shafts. It is transported to the washing-box in

wheelbarrows, and when the washers are about to begin they lay a small

launder, through which there flows on to the iron plate so much water

as is necessary for this washing. Next, a boy throws the metalliferous

material on to the iron plate with an iron shovel and breaks the small

lumps, stirring them this way and that with the same implement. Then the

water and sand penetrating the holes of the plate, fall into the box,

while all the coarse gravel remains on the plate, and this he throws

into a wheelbarrow with the same shovel. Meantime, a younger boy

continually stirs the sand under the plate with a wooden scrubber nearly

as wide as the box, and drives it to the upper end of the box; the

lighter material, as well as a small amount of tin-stone, is carried by

the water down into the underlying trough. The boys carry on this labour

without intermission until they have filled four wheelbarrows with the

coarse and worthless residues, which they carry off and throw away, or

three wheelbarrows if the material is rich in black tin. Then the

foreman has the plank removed which was in front of the iron plate, and

on which the boy stood. The sand, mixed with the tin-stone, is

frequently pushed backward and forward with a scrubber, and the same

sand, because it is lighter, takes the upper place, and is removed as

soon as it appears; that which takes the lower place is turned over with

a spade, in order that any that is light can flow away; when all the

tin-stone is heaped together, he shovels it out of the box and carries

it away. While the foreman does this, one boy with an iron hoe stirs the

sand mixed with fine tin-stone, which has run out of the box and has

settled in the trough and pushes it back to the uppermost part of the

trough, and this material, since it contains a very great amount of

tin-stone, is thrown on to the plate and washed again. The material

which has settled in the lowest part of the trough is taken out

separately and piled in a heap, and is washed on the ordinary strake;

that which has settled in the pool is washed on the canvas strake. In

the summer-time this fruitful labour is repeated more often, in fact ten

or eleven times. The tin-stone which the foreman removes from the box,

is afterward washed in a jigging sieve, and lastly in a tub, where at

length all the sand is separated out. Finally, any material in which are

mixed particles of other metals, can be washed by all these methods,

whether it has been disintegrated from veins or stringers, or whether it

originated from _venae dilatatae_, or from streams and rivers.

[Illustration 345 (Ground Sluicing): A--Launder. B--Cross trough. C--Two

spouts. D--Boxes. E--Plate. F--Grating. G--Shovels. H--Second cross

trough. I--Strake. K--Wooden scrubber. L--Third cross trough.

M--Launder. N--Three-toothed rake.]

The sixth method of washing material of this kind is even more modern

and more useful than the last. Two boxes are constructed, into each of

which water flows through spouts from a cross trough into which it has

been discharged through a pipe or launder. When the material has been

agitated and broken up with iron shovels by two boys, part of it runs

down and falls through the iron plates full of holes, or through the

iron grating, and flows out of the box over a sloping surface into

another cross trough, and from this into a strake seven feet long and

two and a half feet wide. Then the foreman again stirs it with a wooden

scrubber that it may become clean. As for the material which has flowed

down with the water and settled in the third cross trough, or in the

launder which leads from it, a third boy rakes it with a two-toothed

rake; in this way the fine tin-stone settles down and the water carries

off the valueless sand into the creek. This method of washing is most

advantageous, for four men can do the work of washing in two boxes,

while the last method, if doubled, requires six men, for it requires two

boys to throw the material to be washed on to the plate and to stir it

with iron shovels; two more are required with wooden scrubbers to keep

stirring the sand, mixed with the tin-stone, under the plate, and to

push it toward the upper end of the box; further, two foremen are

required to clean the tin-stone in the way I have described. In the

place of a plate full of holes, they now fix in the boxes a grating made

of iron wire as thick as the stalks of rye; that these may not be

depressed by the weight and become bent, three iron bars support them,

being laid crosswise underneath. To prevent the grating from being

broken by the iron shovels with which the material is stirred in

washing, five or six iron rods are placed on top in cross lines, and are

fixed to the box so that the shovels may rub them instead of the

grating; for this reason the grating lasts longer than the plates,

because it remains intact, while the rods, when worn by rubbing, can

easily be replaced by others.

[Illustration 346 (Ground Sluicing): A--Pits. B--Torrent.

C--Seven-pronged fork. D--Shovel.]

Miners use the seventh method of washing when there is no stream of

water in the part of the mountain which contains the black tin, or

particles of gold, or of other metals. In this case they frequently dig

more than fifty ditches on the slope below, or make the same number of

pits, six feet long, three feet wide, and three-quarters of a foot deep,

not any great distance from each other. At the season when a torrent

rises from storms of great violence or long duration, and rushes down

the mountain, some of the miners dig the metalliferous material in the

woods with broad hoes and drag it to the torrent. Other miners divert

the torrent into the ditches or pits, and others throw the roots of

trees, shrubs, and grass out of the ditches or pits with seven-pronged

wooden forks. When the torrent has run down, they remove with shovels

the uncleansed tin-stone or particles of metal which have settled in the

ditches or pits, and cleanse it.

[Illustration 347 (Ground Sluicing): A--Gully. B--Ditch. C--Torrent.

D--Sluice box employed by the Lusitanians.]

The eighth method is also employed in the regions which the Lusitanians

hold in their power and sway, and is not dissimilar to the last. They

drive a great number of deep ditches in rows in the gullies, slopes,

and hollows of the mountains. Into these ditches the water, whether

flowing down from snow melted by the heat of the sun or from rain,

collects and carries together with earth and sand, sometimes tin-stone,

or, in the case of the Lusitanians, the particles of gold loosened from

veins and stringers. As soon as the waters of the torrent have all run

away, the miners throw the material out of the ditches with iron

shovels, and wash it in a common sluice box.

[Illustration 348 (Trough for washing alluvial): A--Trough. B--Launder.

C--Hoe. D--Sieve.]

The Poles wash the impure lead from _venae dilatatae_ in a trough ten

feet long, three feet wide, and one and one-quarter feet deep. It is

mixed with moist earth and is covered by a wet and sandy clay, and so

first of all the clay, and afterward the ore, is dug out. The ore is

carried to a stream or river, and thrown into a trough into which water

is admitted by a little launder, and the washer standing at the lower

end of the trough drags the ore out with a narrow and nearly pointed

hoe, whose wooden handle is nearly ten feet long. It is washed over

again once or twice in the same way and thus made pure. Afterward when

it has been dried in the sun they throw it into a copper sieve, and

separate the very small pieces which pass through the sieve from the

larger ones; of these the former are smelted in a faggot pile and the

latter in the furnace. Of such a number then are the methods of washing.

[Illustration 349 (Tin burning Furnace): A--Furnace. B--Its mouth.

C--Poker. D--Rake with two teeth. E--Hoe.]

One method of burning is principally employed, and two of roasting. The

black tin is burned by a hot fire in a furnace similar to an oven[21];

it is burned if it is a dark-blue colour, or if pyrites and the stone

from which iron is made are mixed with it, for the dark blue colour if

not burnt, consumes the tin. If pyrites and the other stone are not

volatilised into fumes in a furnace of this kind, the tin which is made

from the tin-stone is impure. The tin-stone is thrown either into the

back part of the furnace, or into one side of it; but in the former case

the wood is placed in front, in the latter case alongside, in such a

manner, however, that neither firebrands nor coals may fall upon the

tin-stone itself or touch it. The fuel is manipulated by a poker made of

wood. The tin-stone is now stirred with a rake with two teeth, and now

again levelled down with a hoe, both of which are made of iron. The very

fine tin-stone requires to be burned less than that of moderate size,

and this again less than that of the largest size. While the tin-stone

is being thus burned, it frequently happens that some of the material

runs together.

The burned tin-stone should then be washed again on the strake, for in

this way the material which has been run together is carried away by the

water into the cross-trough, where it is gathered up and worked over,

and again washed on the strake. By this method the metal is separated

from that which is devoid of metal.

[Illustration 350 (Stall Roasting Matte): A--Pits. B--Wood. C--Cakes.

D--Launder.]

Cakes from pyrites, or _cadmia_, or cupriferous stones, are roasted in

quadrangular pits, of which the front and top are open, and these pits

are generally twelve feet long, eight feet wide, and three feet deep.

The cakes of melted pyrites are usually roasted twice over, and those of

_cadmia_ once. These latter are first rolled in mud moistened with

vinegar, to prevent the fire from consuming too much of the copper with

the bitumen, or sulphur, or orpiment, or realgar. The cakes of pyrites

are first roasted in a slow fire and afterward in a fierce one, and in

both cases, during the whole following night, water is let in, in order

that, if there is in the cakes any alum or vitriol or saltpetre capable

of injuring the metals, although it rarely does injure them, the water

may remove it and make the cakes soft. The solidified juices are nearly

all harmful to the metal, when cakes or ore of this kind are smelted.

The cakes which are to be roasted are placed on wood piled up in the

form of a crate, and this pile is fired[22].

[Illustration 351 (Matte Roasting): A--Cakes. B--Bundles of faggots.

C--Furnaces.]

The cakes which are made of copper smelted from schist are first thrown

upon the ground and broken, and then placed in the furnace on bundles of

faggots, and these are lighted. These cakes are generally roasted seven

times and occasionally nine times. While this is being done, if they are

bituminous, then the bitumen burns and can be smelled. These furnaces

have a structure like the structure of the furnaces in which ore is

smelted, except that they are open in front; they are six feet high and

four feet wide. As for this kind of furnace, three of them are required

for one of those in which the cakes are melted. First of all they are

roasted in the first furnace, then when they are cooled, they are

transferred into the second furnace and again roasted; later they are

carried to the third, and afterward back to the first, and this order is

preserved until they have been roasted seven or nine times.

END OF BOOK VIII.

FOOTNOTES:

[1] As would be expected, practically all the technical terms used by

Agricola in this chapter are adaptations. The Latin terms, _canalis_,

_area_, _lacus_, _vasa_, _cribrum_, and _fossa_, have had to be pressed

into service for many different devices, largely by extemporised

combinations. Where the devices described have become obsolete, we have

adopted the nomenclature of the old works on Cornish methods. The

following examples may be of interest:--

Simple buddle = _Canalis simplex_

Divided buddle = _Canalis tabellis distinctus_

Ordinary strake = _Canalis devexus_

Short strake = _Area curta_

Canvas strake = _Area linteis extensis contecta_

Limp = _Radius_.

The strake (or streke) when applied to alluvial tin, would have been

termed a "tye" in some parts of Cornwall, and the "short strake" a

"gounce." In the case of the stamp mill, inasmuch as almost every

mechanical part has its counterpart in a modern mill, we have considered

the reader will have less difficulty if the modern designations are used

instead of the old Cornish. The following are the essential terms in

modern, old Cornish, and Latin:--

Stamp Stamper _Pilum_

Stamp-stem Lifter _Pilum_

Shoes Stamp-heads _Capita_

Mortar-box Box _Capsa_

Cam-shaft Barrell _Axis_

Cams Caps _Dentes_

Tappets Tongues _Pili dentes_

Screen Crate _Laminae foraminum plenae_

Settling pit Catchers _Lacus_

Jigging sieve Dilleugher _Cribrum angustum_

[2] Agricola uses four Latin verbs in connection with heat operations at

temperatures under the melting point: _Calefacio_, _uro_, _torreo_, and

_cremo_. The first he always uses in the sense of "to warm" or "to

heat," but the last three he uses indiscriminately in much the same way

as the English verbs burn, roast, and calcine are used; but in general

he uses the Latin verbs in the order given to indicate degrees of heat.

We have used the English verbs in their technical sense as indicated by

the context.

It is very difficult to say when roasting began as a distinct and

separate metallurgical step in sulphide ore treatment. The Greeks and

Romans worked both lead and copper sulphides (see note on p. 391, and

note on p. 403), but neither in the remains of old works nor in their

literature is there anything from which satisfactory details of such a

step can be obtained. The Ancients, of course, understood lime-burning,

and calcined several salts to purify them or to render them more

caustic. Practically the only specific mention is by Pliny regarding

lead ores (see p. 391). Even the statement of Theophilus (1050-1100,

A.D.), may refer simply to rendering ore more fragile, for he says (p.

305) in regard to copper ore: "This stone dug up in abundance is placed

upon a pile and burned (_comburitur_) after the manner of lime. Nor does

it change colour, but loses its hardness and can be broken up, and

afterward it is smelted." The _Probierbuechlein_ casually mentions

roasting prior to assaying, and Biringuccio (III, 2) mentions

incidentally that "dry and ill-disposed ores before everything must be

roasted in an open oven so that the air can get in." He gives no further

information; and therefore this account of Agricola's becomes

practically the first. Apparently roasting, as a preliminary to the

treatment of copper sulphides, did not come into use in England until

some time later than Agricola, for in Col. Grant Francis' "Smelting of

Copper in the Swansea District" (London, 1881, p. 29), a report is set

of the "Doeinges of Jochim Ganse"--an imported German--at the "Mynes by

Keswicke in Cumberland, A.D., 1581," wherein the delinquencies of the

then current practice are described: "Thei never coulde, nether yet can

make (copper) under XXII. tymes passinge thro the fire, and XXII. weekes

doeing thereof ane sometyme more. But now the nature of these IX.

hurtfull humors abovesaid being discovered and opened by Jochim's way of

doeing, we can, by his order of workeinge, so correct theim, that parte

of theim beinge by nature hurtfull to the copper in wasteinge of it, ar

by arte maide freindes, and be not onely an encrease to the copper, but

further it in smeltinge; and the rest of the other evill humors shalbe

so corrected, and their humors so taken from them, that by once

rosteinge and once smeltinge the ure (which shalbe done in the space of

three dayes), the same copper ure shall yeeld us black copper." Jochim

proposed by 'rostynge' to be rid of "sulphur, arsineque, and antimony."

[3] _Orpiment_ and _realgar_ are the red and yellow arsenical sulphides.

(See note on p. 111).

[4] _Cadmia bituminosa_. The description of this substance by Agricola,

given below, indicates that it was his term for the complex

copper-zinc-arsenic-cobalt minerals found in the well-known, highly

bituminous, copper schists at Mannsfeld. The later Mineralogists,

Wallerius (_Mineralogia_, Stockholm, 1747), Valmont De Bomare

(_Mineralogie_, Paris, 1762), and others assume Agricola's _cadmia

bituminosa_ to be "black arsenic" or "arsenic noir," but we see no

reason for this assumption. Agricola's statement (_De Nat. Foss._, p.

369) is "... the schistose stone dug up at the foot of the Melibocus

Mountains, or as they are now called the Harz (_Hercynium_), near

Eisleben, Mannsfeld, and near Hettstedt, is similar to _spinos_ (a

bituminous substance described by Theophrastus), if not identical with

it. This is black, bituminous, and cupriferous, and when first extracted

from the mine it is thrown out into an open space and heaped up in a

mound. Then the lower part of the mound is surrounded by faggots, on to

which are likewise thrown stones of the same kind. Then the faggots are

kindled and the fire soon spreads to the stones placed upon them; by

these the fire is communicated to the next, which thus spreads to the

whole heap. This easy reception of fire is a characteristic which

bitumen possesses in common with sulphur. Yet the small, pure and black

bituminous ore is distinguished from the stones as follows: when they

burn they emit the kind of odour which is usually given off by burning

bituminous coal, and besides, if while they are burning a small shower

of rain should fall, they burn more brightly and soften more quickly.

Indeed, when the wind carries the fumes so that they descend into nearby

standing waters, there can be seen floating in it something like a

bituminous liquid, either black, or brown, or purple, which is

sufficient to indicate that those stones were bituminous. And that genus

of stones has been recently found in the Harz in layers, having

occasionally gold-coloured specks of pyrites adhering to them,

representing various flat sea-fish or pike or perch or birds, and

poultry cocks, and sometimes salamanders."

[5] _Atramentum sutorium rubrum_. Literally, this would be red vitriol.

The German translation gives _rot kupferwasser_, also red vitriol. We

must confess that we cannot make this substance out, nor can we find it

mentioned in the other works of Agricola. It may be the residue from

leaching roasted pyrites for vitriol, which would be reddish oxide of

iron.

[6] The statement "elsewhere" does not convey very much more

information. It is (_De Nat. Fos._, p. 253): "When Goslar pyrites and

Eisleben (copper) schists are placed on the pyre and roasted for the

third time, they both exude a certain substance which is of a greenish

colour, dry, rough, and fibrous (_tenue_). This substance, like

asbestos, is not consumed by the fire. The schists exude it more

plentifully than the pyrites." The _Interpretatio_ gives _federwis_, as

the German equivalent of _amiantus_ (asbestos). This term was used for

the feathery alum efflorescence on aluminous slates.

[7] Bearing in mind that bituminous cadmia contained arsenical-cobalt

minerals, this substance "resembling _pompholyx_" would probably be

arsenic oxide. In _De Natura Fossilium_ (p. 368). Agricola discusses the

_pompholyx_ from _cadmia_ at length and pronounces it to be of

remarkably "corrosive" quality. (See also note on p. 112.)

[8] HISTORICAL NOTE ON CRUSHING AND CONCENTRATION OF ORES. There can be

no question that the first step in the metallurgy of ores was direct

smelting, and that this antedates human records. The obvious advantages

of reducing the bulk of the material to be smelted by the elimination of

barren portions of the ore, must have appealed to metallurgists at a

very early date. Logically, therefore, we should find the second step in

metallurgy to be concentration in some form. The question of crushing is

so much involved with concentration that we have not endeavoured to keep

them separate. The earliest indication of these processes appears to be

certain inscriptions on monuments of the IV Dynasty (4,000 B.C.?)

depicting gold washing (Wilkinson, The Ancient Egyptians, London, 1874,

II, p. 137). Certain stelae of the XII Dynasty (2,400 B.C.) in the

British Museum (144 Bay 1 and 145 Bay 6) refer to gold washing in the

Sudan, and one of them appears to indicate the working of gold ore as

distinguished from alluvial. The first written description of the

Egyptian methods--and probably that reflecting the most ancient

technology of crushing and concentration--is that of Agatharchides, a

Greek geographer of the second Century B.C. This work is lost, but the

passage in question is quoted by Diodorus Siculus (1st Century B.C.) and

by Photius (died 891 A.D.). We give Booth's translation of Diodorus

(London, 1700, p. 89), slightly amended: "In the confines of Egypt and

the neighbouring countries of Arabia and Ethiopia there is a place full

of rich gold mines, out of which with much cost and pains of many

labourers gold is dug. The soil here is naturally black, but in the body

of the earth run many white veins, shining like white marble, surpassing

in lustre all other bright things. Out of these laborious mines, those

appointed overseers cause the gold to be dug up by the labour of a vast

multitude of people. For the Kings of Egypt condemn to these mines

notorious criminals, captives taken in war, persons sometimes falsely

accused, or against whom the King is incens'd; and not only they

themselves, but sometimes all their kindred and relations together with

them, are sent to work here, both to punish them, and by their labour to

advance the profit and gain of the Kings. There are infinite numbers

upon these accounts thrust down into these mines, all bound in fetters,

where they work continually, without being admitted any rest night or

day, and so strictly guarded that there is no possibility or way left to

make an escape. For they set over them barbarians, soldiers of various

and strange languages, so that it is not possible to corrupt any of the

guard by discoursing one with another, or by the gaining insinuations of

familiar converse. The earth which is hardest and full of gold they

soften by putting fire under it, and then work it out with their hands.

The rocks thus soften'd and made more pliant and yielding, several

thousands of profligate wretches break in pieces with hammers and

pickaxes. There is one artist that is the overseer of the whole work,

who marks out the stone, and shows the labourers the way and manner how

he would have it done. Those that are the strongest amongst them that

are appointed to this slavery, provided with sharp iron pickaxes, cleave

the marble-shining rock by mere force and strength, and not by arts or

sleight-of-hand. They undermine not the rock in a direct line, but

follow the bright shining vein of the mine. They carry lamps fastened to

their foreheads to give them light, being otherwise in perfect darkness

in the various windings and turnings wrought in the mine; and having

their bodies appearing sometimes of one colour and sometimes of another

(according to the nature of the mine where they work) they throw the

lumps and pieces of the stone cut out of the rock upon the floor. And

thus they are employed continually without intermission, at the very nod

of the overseer, who lashes them severely besides. And there are little

boys who penetrate through the galleries into the cavities and with

great labour and toil gather up the lumps and pieces hewed out of the

rock as they are cast upon the ground, and carry them forth and lay them

upon the bank. Those that are over thirty years of age take a piece of

the rock of such a certain quantity, and pound it in a stone mortar with

iron pestles till it be as small as a vetch; then those little stones so

pounded are taken from them by women and older men, who cast them into

mills that stand together there near at hand in a long row, and two or

three of them being employed at one mill they grind a certain measure

given to them at a time, until it is as small as fine meal. No care at

all is taken of the bodies of these poor creatures, so that they have

not a rag so much as to cover their nakedness, and no man that sees them

can choose but commiserate their sad and deplorable condition. For

though they are sick, maimed, or lame, no rest nor intermission in the

least is allowed them; neither the weakness of old age, nor women's

infirmities are any plea to excuse them; but all are driven to their

work with blows and cudgelling, till at length, overborne with the

intolerable weight of their misery, they drop down dead in the midst of

their insufferable labours; so that these miserable creatures always

expect the future to be more terrible than even the present, and

therefore long for death as far more desirable than life.

"At length the masters of the work take the stone thus ground to powder,

and carry it away in order to perfect it. They spread the mineral so

ground upon a broad board, somewhat sloping, and pouring water upon it,

rub it and cleanse it; and so all the earthy and drossy part being

separated from the rest by the water, it runs off the board, and the

gold by reason of its weight remains behind. Then washing it several

times again, they first rub it lightly with their hands; afterward they

draw off any earthy and drossy matter with slender sponges gently

applied to the powdered dust, till it be clean, pure gold. At last other

workmen take it away by weight and measure, and these put it into

earthen pots, and according to the quantity of the gold in every pot

they mix with it some lead, grains of salt, a little tin and barley

bran. Then, covering every pot close, and carefully daubing them over

with clay, they put them in a furnace, where they abide five days and

nights together; then after a convenient time that they have stood to

cool, nothing of the other matter is to be found in the pots but only

pure, refined gold, some little thing diminished in the weight. And thus

gold is prepared in the borders of Egypt, and perfected and completed

with so many and so great toils and vexations. And, therefore, I cannot

but conclude that nature itself teaches us, that as gold is got with

labour and toil, so it is kept with difficulty; it creates everywhere

the greatest cares; and the use of it is mixed both with pleasure and

sorrow."